Chevy Cruze - Battery Draw - Eric O Gets A Learning Lesson
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Date: 2025-03-08
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Comments and reviews: 20
WreckDiver99
$87 for a quite literally $3 relay. Yep. People wonder why they junk cars that could probably get another 100K miles or more out of them. well when you make a basic part $87 making a basic repair unobtainium to many Yea. Used to work for one of the car companies and had access to the parts database. I'd see our parts department buying parts for $5 and the dealership was saying Yea, that's $100, going back to the database you'd see the uplift of 300% (which was actually fairly common for parts. So the parts group would sell the $5 part for $15, and the Stealership would turn around and sell it for $45 to get their cut. The people making the parts knew this was going on, so they sell in the aftermarket for a tad under the parts department costs.
I get it, companies need to make a profit, if you aren't making a profit you're going to die. People are angry that places like Ford made $11B. HOW HORRIBLE they are. Well, that $11B will have $1B used right off to fund the UAW bonuses, healthcare increases, and more. Another $2. 5B will be used to fund the next major F-Series launch (yea, it costs BILLIONS to develop a new vehicle, even a basic refresh cost $750M to $1B now. It isn't 'corporate greed', as much as people want to scream, it's Costs have gone out of control, and what was needed in 2019 vs. today is more than DOUBLE in 4 years. People saying it's the CEO pay While high, I wouldn't (couldn't) do their job. Pay them $0 pay the entire Top Management $0. nothing, not even stock options. you just gave employees $10. big picture people.
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$87 for a quite literally $3 relay. Yep. People wonder why they junk cars that could probably get another 100K miles or more out of them. well when you make a basic part $87 making a basic repair unobtainium to many Yea. Used to work for one of the car companies and had access to the parts database. I'd see our parts department buying parts for $5 and the dealership was saying Yea, that's $100, going back to the database you'd see the uplift of 300% (which was actually fairly common for parts. So the parts group would sell the $5 part for $15, and the Stealership would turn around and sell it for $45 to get their cut. The people making the parts knew this was going on, so they sell in the aftermarket for a tad under the parts department costs.
I get it, companies need to make a profit, if you aren't making a profit you're going to die. People are angry that places like Ford made $11B. HOW HORRIBLE they are. Well, that $11B will have $1B used right off to fund the UAW bonuses, healthcare increases, and more. Another $2. 5B will be used to fund the next major F-Series launch (yea, it costs BILLIONS to develop a new vehicle, even a basic refresh cost $750M to $1B now. It isn't 'corporate greed', as much as people want to scream, it's Costs have gone out of control, and what was needed in 2019 vs. today is more than DOUBLE in 4 years. People saying it's the CEO pay While high, I wouldn't (couldn't) do their job. Pay them $0 pay the entire Top Management $0. nothing, not even stock options. you just gave employees $10. big picture people.
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Dave-ei7kk
I’m just an old DIYer but somewhere along the line I did learn what a latching relay is and was puzzled when you seemed to confuse what you were seeing on the load side of that relay with a closed which is just one of two possible states for a latching relay. So your journey of discovery was quite interesting to me as It confirmed what I thought I remembered from a long time ago.
Regarding the theory of operation for that circuit I suspect that the relay is normally latched in the closed position so that the OnStar telematics module can remain powered for awhile when the ignition is switched off. But as the battery voltage drops the module that controls this relay (BCM) commands it to latch in the off position to save the battery from being discharged. And since keeping the relay coil energized to maintain its state would defeat the intent to eliminate parasitic draw, a latching relay which doesn’t need power to maintain its state, is used. Hence the description Battery Saver. Once the car is started the relay is commanded to latch in the on position. Rinse and repeat the next time the ignition is turned off.
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I’m just an old DIYer but somewhere along the line I did learn what a latching relay is and was puzzled when you seemed to confuse what you were seeing on the load side of that relay with a closed which is just one of two possible states for a latching relay. So your journey of discovery was quite interesting to me as It confirmed what I thought I remembered from a long time ago.
Regarding the theory of operation for that circuit I suspect that the relay is normally latched in the closed position so that the OnStar telematics module can remain powered for awhile when the ignition is switched off. But as the battery voltage drops the module that controls this relay (BCM) commands it to latch in the off position to save the battery from being discharged. And since keeping the relay coil energized to maintain its state would defeat the intent to eliminate parasitic draw, a latching relay which doesn’t need power to maintain its state, is used. Hence the description Battery Saver. Once the car is started the relay is commanded to latch in the on position. Rinse and repeat the next time the ignition is turned off.
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SeanBZA
That relay is a bistable relay, there so you can use a scan tool to drop the vehicle into shipping mode, disabling almost all the loads off the battery for shipping. disables radio standby and telematics modules, leaving the BCM only alive, and that is in a deep sleep mode till a door is opened, when it will wake up and wait for an OBD command to enable the regular mode, or an ignition operation, which will cause the relay to operate and apply the radio and telematics again. It needs a pulse on the one coil to close it, and a pulse on the other side to open it, as you found out.
The relay is not the failure, more likely the Onstar module is failed, transmitting all the time, so disconnecting it will work better. That relay is only used from the factory when shipping the vehicle, so it can be loaded on a ship, OBD commanded to off, and thus the battery is able to be saved for the 6 week shipping to the final port, and there it will be enabled to drive the vehicle off the ship. then might be enabled for road shipping, and for warehouse storage in the main dealership.
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That relay is a bistable relay, there so you can use a scan tool to drop the vehicle into shipping mode, disabling almost all the loads off the battery for shipping. disables radio standby and telematics modules, leaving the BCM only alive, and that is in a deep sleep mode till a door is opened, when it will wake up and wait for an OBD command to enable the regular mode, or an ignition operation, which will cause the relay to operate and apply the radio and telematics again. It needs a pulse on the one coil to close it, and a pulse on the other side to open it, as you found out.
The relay is not the failure, more likely the Onstar module is failed, transmitting all the time, so disconnecting it will work better. That relay is only used from the factory when shipping the vehicle, so it can be loaded on a ship, OBD commanded to off, and thus the battery is able to be saved for the 6 week shipping to the final port, and there it will be enabled to drive the vehicle off the ship. then might be enabled for road shipping, and for warehouse storage in the main dealership.
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mikerobbins5049
Good job Eric O. You followed the logical (to you) path and found the problem. You learned something in the process. As a former high school shop teacher (33 yrs, any time you learn something it’s not a waste of time. I learned something today and I’m 72. My normal auto tech shop was not open and I had a problem so I went to another shop. I learned I’ll never go to that shop again. First off, they weren’t open on time, took them way to long to fix the problem (A very simple fix, they tried to upsell me some stuff I didn’t really need, and they charged way to much for the small job they did. I seriously don’t know what I’ll do if my auto tech guy decides to retire. I guess I’ll start shipping my vehicles to South Main Auto for diag and repair.
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Good job Eric O. You followed the logical (to you) path and found the problem. You learned something in the process. As a former high school shop teacher (33 yrs, any time you learn something it’s not a waste of time. I learned something today and I’m 72. My normal auto tech shop was not open and I had a problem so I went to another shop. I learned I’ll never go to that shop again. First off, they weren’t open on time, took them way to long to fix the problem (A very simple fix, they tried to upsell me some stuff I didn’t really need, and they charged way to much for the small job they did. I seriously don’t know what I’ll do if my auto tech guy decides to retire. I guess I’ll start shipping my vehicles to South Main Auto for diag and repair.
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JASPACB750RR
A latching relay is a relay that remembers the last state it was in.
Let’s use GMs auto start/stop feature. A normal relay controls that, you turn the feature off when driving, shit the vehicle off, restart it and it’s back on.
Installing a latching relay in line would mean the first time you turned it off, it would latch to that off position. And even after turning the vehicle off and back on it will still remember the latched off position and you’ll be good, no more auto start/stop shenanigans.
Which is what they should do from the factory. If you want that feature, turn it on and it’ll remember for you.
But I hate it in my truck and got tired of it so I put a latching relay in to eliminate the button press every time I got in the truck.
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A latching relay is a relay that remembers the last state it was in.
Let’s use GMs auto start/stop feature. A normal relay controls that, you turn the feature off when driving, shit the vehicle off, restart it and it’s back on.
Installing a latching relay in line would mean the first time you turned it off, it would latch to that off position. And even after turning the vehicle off and back on it will still remember the latched off position and you’ll be good, no more auto start/stop shenanigans.
Which is what they should do from the factory. If you want that feature, turn it on and it’ll remember for you.
But I hate it in my truck and got tired of it so I put a latching relay in to eliminate the button press every time I got in the truck.
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levithompson4619
Being able to be in this career for 12 yrs im grateful and had a butt kicked several times but being able to learn from it and get better makes us all better technicians. Even though could never be as good as you sir. Im always learning everyday. Crazy that you could be in this career for so long and still learn something new. Will definitely make it always interesting and will make us never get bored from doing the same thing. That's what I love about this career even though sometimes I wonder why I chose it like I'm sure we all do lol! But great video like always keep up the outstanding work and effort you put into everything sir thank you!
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Being able to be in this career for 12 yrs im grateful and had a butt kicked several times but being able to learn from it and get better makes us all better technicians. Even though could never be as good as you sir. Im always learning everyday. Crazy that you could be in this career for so long and still learn something new. Will definitely make it always interesting and will make us never get bored from doing the same thing. That's what I love about this career even though sometimes I wonder why I chose it like I'm sure we all do lol! But great video like always keep up the outstanding work and effort you put into everything sir thank you!
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grahamstaffen
I empathize! Learned about latching when replacing the main power switch on my Windows PC. These switches are normally non latching (or transient) which means you push it, contact is made, PC comes to life, then you release and contact is broken. However, the PC remains on because of that transient contact. The replacement switch was a latched switch (longer story) so now you must push once to make contact and then once again to break contact. Two inputs required to make it work correctly for the machine, just like your green relay! Failure to push it again would maintain contact and the PC would power down. The stuff you learn, the hard way!
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I empathize! Learned about latching when replacing the main power switch on my Windows PC. These switches are normally non latching (or transient) which means you push it, contact is made, PC comes to life, then you release and contact is broken. However, the PC remains on because of that transient contact. The replacement switch was a latched switch (longer story) so now you must push once to make contact and then once again to break contact. Two inputs required to make it work correctly for the machine, just like your green relay! Failure to push it again would maintain contact and the PC would power down. The stuff you learn, the hard way!
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doughavard5130
40 years as an industrial electrician, when you said it's got two controls and is a latching relay, I almost yelled into the video. I knew what a latching relay was, and how they worked. Given you figured it out, I wouldn't be too hard on yourself. Like you say, you always remember the lessons that you learn the hard way. The amount of information you know about vehicle mechanical and electrical systems is truly impressive, but no one knows everything. If you hadn't made this video, we would not know that you didn't know. So now we know. You know. Thanks for all the interesting videos you post.
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40 years as an industrial electrician, when you said it's got two controls and is a latching relay, I almost yelled into the video. I knew what a latching relay was, and how they worked. Given you figured it out, I wouldn't be too hard on yourself. Like you say, you always remember the lessons that you learn the hard way. The amount of information you know about vehicle mechanical and electrical systems is truly impressive, but no one knows everything. If you hadn't made this video, we would not know that you didn't know. So now we know. You know. Thanks for all the interesting videos you post.
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autorepair
I'm fairly sure this will get buried but if you ever run into this again on the windshield is a plastic black cover. That is where the sensor for the key fob (I dont remember the offical name lol) and the OnStar connection live. Unplug the little black 6 pin connector and move on. I hated the idea of being able to be tracked and remotely shut down so I went snooping on what to do to disable it completely and it was actually really simple! I have a 14. Maybe when the wifey gets home I'll go take a peek at the fuse box (that I had NO idea flipped down) and see if I have that green relay.
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I'm fairly sure this will get buried but if you ever run into this again on the windshield is a plastic black cover. That is where the sensor for the key fob (I dont remember the offical name lol) and the OnStar connection live. Unplug the little black 6 pin connector and move on. I hated the idea of being able to be tracked and remotely shut down so I went snooping on what to do to disable it completely and it was actually really simple! I have a 14. Maybe when the wifey gets home I'll go take a peek at the fuse box (that I had NO idea flipped down) and see if I have that green relay.
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davidut55
I figured a few minutes ahead of you, that it might be a no spring return relay!
My experience today was with an oil pressure sensor, the brand name was HELLA! Not a bad name, but not even a month old and was intermittently flashing the oil light! With too much confidence in HELLA brand, replaced the oil pump also! And guess what, THE OIL LIGHT STILL ON, intermittently!
God a brand new GENUINE vw sensor, and tested them both. The new one 800 mB closes 0 ohms, the old/new one(HELLA is the name, 3k ohms at 3000 mB, yes 3 bar pressure!
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I figured a few minutes ahead of you, that it might be a no spring return relay!
My experience today was with an oil pressure sensor, the brand name was HELLA! Not a bad name, but not even a month old and was intermittently flashing the oil light! With too much confidence in HELLA brand, replaced the oil pump also! And guess what, THE OIL LIGHT STILL ON, intermittently!
God a brand new GENUINE vw sensor, and tested them both. The new one 800 mB closes 0 ohms, the old/new one(HELLA is the name, 3k ohms at 3000 mB, yes 3 bar pressure!
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virtisconsole12
Power probe to the rescue. yeah I’ve been a DIYer for 45 years and would have followed pretty much same course of action. starting with high current terminals. my initial thought would have been as a GM go to blower motor control module. GMs notorious for HVAC system parasitic draws. and don’t sell yourself short as a Elec Engineer MS grad I have never come across that type of a relay either. nevertheless fuse 1 is feeding something pulling 400ma but probably not worth digging into. great video and tutorial as always
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Power probe to the rescue. yeah I’ve been a DIYer for 45 years and would have followed pretty much same course of action. starting with high current terminals. my initial thought would have been as a GM go to blower motor control module. GMs notorious for HVAC system parasitic draws. and don’t sell yourself short as a Elec Engineer MS grad I have never come across that type of a relay either. nevertheless fuse 1 is feeding something pulling 400ma but probably not worth digging into. great video and tutorial as always
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throttlebottle5906
they must use the physical latching type so it stays on regardless of ignition switch/bcm power suddenly being cut, which is likely in case of a wreck or other problem. then it will only go off when powered off by the BCM, the on and off coils only need short duration power pulses to operate, then not need powered anymore.
so as long as battery/main fuses and internal box is in tact the onstar/safety/occupancy junk can continue to work, while everything else goes to sleep mode using lowest power possible.
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they must use the physical latching type so it stays on regardless of ignition switch/bcm power suddenly being cut, which is likely in case of a wreck or other problem. then it will only go off when powered off by the BCM, the on and off coils only need short duration power pulses to operate, then not need powered anymore.
so as long as battery/main fuses and internal box is in tact the onstar/safety/occupancy junk can continue to work, while everything else goes to sleep mode using lowest power possible.
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shepherdguy
I am not a mechanic by trade but after working on my own cars over many many years, along with family that take advantage of my knowledge of cars, i have gained enough knowledge that it seems like I can fix and troubleshoot almost anything ( with a big emphasis on seems like. Some of what I learned, I learned from you and ScannerDanner. But until today, I knew nothing about latching relays. But guess what Now I know about latching relays, so if I ever run into one, I'll know, and shame on me if I don't remember!
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I am not a mechanic by trade but after working on my own cars over many many years, along with family that take advantage of my knowledge of cars, i have gained enough knowledge that it seems like I can fix and troubleshoot almost anything ( with a big emphasis on seems like. Some of what I learned, I learned from you and ScannerDanner. But until today, I knew nothing about latching relays. But guess what Now I know about latching relays, so if I ever run into one, I'll know, and shame on me if I don't remember!
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peterperpetua2974
Years ago, I bought Trailblazer. It did not have fog lights which I wanted. I put on the fog lights (original type, but I wanted it to work light original equipment. I bought a headlight switch (Original) but wanted to make it work and light up the factory would. There BCM was not programed for fog lights. To get around this I went on eBay and bought a Latching Relay which I wired in, and it worked perfectly. This is the only time in over 50 years of being a technician I ever delt with a latching relay.
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Years ago, I bought Trailblazer. It did not have fog lights which I wanted. I put on the fog lights (original type, but I wanted it to work light original equipment. I bought a headlight switch (Original) but wanted to make it work and light up the factory would. There BCM was not programed for fog lights. To get around this I went on eBay and bought a Latching Relay which I wired in, and it worked perfectly. This is the only time in over 50 years of being a technician I ever delt with a latching relay.
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kerryp1525
It's not the latching relay that screwed you up, It's the lack of an explanation of what that
battery save circuit was trying to do and you had NO way to know why it was being commanded, Unhooking the On Star was the only real course you had to fix this one.
One other person commented that it was looking for a Three G network b4 shutting down! Who Knows Chevrolet probably can't answer that one! Good work Eric. These parasitic draw problems are almost NEVER easy. You Da Man!
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It's not the latching relay that screwed you up, It's the lack of an explanation of what that
battery save circuit was trying to do and you had NO way to know why it was being commanded, Unhooking the On Star was the only real course you had to fix this one.
One other person commented that it was looking for a Three G network b4 shutting down! Who Knows Chevrolet probably can't answer that one! Good work Eric. These parasitic draw problems are almost NEVER easy. You Da Man!
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HueToobBlows
Not trying to be a jerk but a latching relay is a momentary input to turn on and the relay then latches closed. Another momentary input and the relay unlatches to open.
It doesn't require a continuous input like an on/off switch rather just a momentary push button, or in this case, hazards/vehicle on/ hold button sequence.
Most only use one input- sending voltage down the same wire turns relay on/off. This one uses separate ones to accomplish the same thing.
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Not trying to be a jerk but a latching relay is a momentary input to turn on and the relay then latches closed. Another momentary input and the relay unlatches to open.
It doesn't require a continuous input like an on/off switch rather just a momentary push button, or in this case, hazards/vehicle on/ hold button sequence.
Most only use one input- sending voltage down the same wire turns relay on/off. This one uses separate ones to accomplish the same thing.
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inothome
Also known as a bi-stable relay. Used in a lot of PLC applications as well as in my field of electric utilities in the RTUs and some other substation equipment to helps keep your lights on.
Always good to learn new things.
Some have a physical latch to hold the contacts closed in the NO position and some actually use magnetism to keep the armature in one direction or the other.
Now you learned too much information.
Still ironic it was fuse numero uno!
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Also known as a bi-stable relay. Used in a lot of PLC applications as well as in my field of electric utilities in the RTUs and some other substation equipment to helps keep your lights on.
Always good to learn new things.
Some have a physical latch to hold the contacts closed in the NO position and some actually use magnetism to keep the armature in one direction or the other.
Now you learned too much information.
Still ironic it was fuse numero uno!
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samuhell14
Subaru got a similar issue with the starlink system trying to phone home as well. Don't beat yourself over it Eric, I was on the struggle bus for a bit until I found a TSB about it and I'm sure many of us were too. Also, this is NOT how a car should behave nor what a mechanic should have to deal with. A battery drain because the 3G network is getting disabled across the country was not how I envisioned the profession when I first started over decade ago
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Subaru got a similar issue with the starlink system trying to phone home as well. Don't beat yourself over it Eric, I was on the struggle bus for a bit until I found a TSB about it and I'm sure many of us were too. Also, this is NOT how a car should behave nor what a mechanic should have to deal with. A battery drain because the 3G network is getting disabled across the country was not how I envisioned the profession when I first started over decade ago
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antonchigurh981
I work in industrial automation at an auto manufacturing plant.
As soon as you mentioned that relay appeared to have two different power sources in the diagram, i knew it was a latching relay and when you pulled it out and it said latching i wanted to be able to call the shop and tell you lol.
We also refer to them as keep relays. They NC even when voltage is pulled and need the voltage signal applied to the other side to Open it.
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I work in industrial automation at an auto manufacturing plant.
As soon as you mentioned that relay appeared to have two different power sources in the diagram, i knew it was a latching relay and when you pulled it out and it said latching i wanted to be able to call the shop and tell you lol.
We also refer to them as keep relays. They NC even when voltage is pulled and need the voltage signal applied to the other side to Open it.
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robertandrews5506
Im 44 years in the commercial printer service that has seen the evolution of the blend of software and hardware electro mechanical components. I have worked with a guy Hum InterestingMike. I always looked over his shoulder and he would ask me are you following me Most of the time by then I left the chat. The best lessons leaned were me backtracking the steps he took and that light bull moment was always punctuated with Hum Interesting.
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Im 44 years in the commercial printer service that has seen the evolution of the blend of software and hardware electro mechanical components. I have worked with a guy Hum InterestingMike. I always looked over his shoulder and he would ask me are you following me Most of the time by then I left the chat. The best lessons leaned were me backtracking the steps he took and that light bull moment was always punctuated with Hum Interesting.
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