Ignition relay not receiving signal, not starting?

WESTONADAMS

MEMBER
2005 CHEVROLET EQUINOX
3.4L
6 CYL
AUTOMATIC
250,000 MILES

Hello,

To be succinct, my vehicle isn't starting. (:

I am able to jump the relay with a paperclip, and it fires up. So, the solenoid and battery are in good shape.

I have dash lights, and when I turn my ignition to "start" all the dash lights go out momentarily as if the vehicle will start. So apparently the ignition itself is OK. But the vehicle doesn't start. There's just the sound of a relay or two clicking.

I've swapped out the ignition relay, and it doesn't change anything. So, it's not a bad relay apparently.

The only thing that I know of that may be the culprit is either a grounding issue or one of the computers.

I've tested the resistance from the negative terminal of the battery to the engine engine, and I have next to no resistance. So everything should be grounded well. That leaves the computers as the culprit.

I was about to send in my BCM for testing and possible repair, because it has 71 trouble codes in it, and I've had quite a few other odd issues crop up all of a sudden. However, I thought that ignition was more of an ECM thing. And some of the other electrical issues I've had have been engine related. So, I don't know why the BCM would have all the trouble codes if the symptoms are more engine related.

But I know the computers are all interconnected.

If someone knows how I can single out either the ECM or the BCM as the culprit, it could save me an expensive process of elimination. Thanks!

11 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

The fact that the BCM has 71 codes means it is bad, here is how to change it out, you can get a preprogrammed unit by searching Google or Ebay. Check out the images (below). Please let us know if you need anything else to get the problem fixed.

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Thursday, July 6th, 2023 AT 10:07 AM

WESTONADAMS

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Okay. I am getting close to sending in this BCM for testing and repair. Pardon my many questions, but I just want to confirm.

The XTool D9 scanner I used listed 81 codes under the "BCM." Many of these codes have to do with the body (auxiliary port, windshield wiper, etc.) But some of them have to do with other things (gearshift unlock, ignition, ABS, ECU malfunction, communication codes, etc.).

Am I correct in understanding that even though some of these codes are part of the engine and/or powertrain system, the fact that they are listed under the BCM by my code reader means that the BCM is the culprit? In other words, the BCM is just affecting other parts of the computer system via the CAN?

I realize that it's not always possible to diagnose with 100% certainty, but if possible, I want to avoid sending in my BCM and then having to send in another computer module later.

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Wednesday, July 12th, 2023 AT 2:04 PM

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

Yep, I understand, yes, the BCM can cause issues within other systems inside the CANBUS. The fact that it has so many codes, it sounds like the BCM is bad, but you may want to check the ground and power circuits.

here is a guide to help and the BCM wiring diagrams below which will show you which wires to test:

https://www.2carpros.com/articles/how-to-check-wiring

The ground is behind the right kick panel. Check out the images (below). Please let us know what happens.

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Thursday, July 13th, 2023 AT 9:49 AM

WESTONADAMS

MEMBER
10 POSTS

I cleaned the ground and confirmed that we've got a solid ground from the BCM to the chassis.

I tested the "IGN 1 Voltage" and the "IGN 3 Voltage" coming from the fuse box. I don't know what these designations mean, but both the pink wire and the brown wire coming from the fuse box are carrying good voltage.

The two red "Battery Positive Voltage" wires are also carrying good voltage.

I'm guessing my next step is to send in the BCM for testing.

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Thursday, July 13th, 2023 AT 6:58 PM

KEN L

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Yep, that is what I would do, please let me know how it goes, have a great day!

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Friday, July 14th, 2023 AT 9:11 AM

WESTONADAMS

MEMBER
10 POSTS

Hello again, I just wanted to follow up. Thanks for all the tips.

I sent in my BCM for testing, and they said that it was bad. They replaced it with a remanufactured BCM.

I installed the new BCM and went through the relearning or reprogramming process (a series of turning the key to the start position and waiting and repeating). From what I recall, there was a lock light on the dash immediately after I installed the BCM, but the lock light disappeared after I went through the process. However, the car still does not start. I am not able to jump it anymore either. It fires up, but then dies after about 2 seconds. I had a mechanic friend of mine look at it. He put his computer on the vehicle and found very confusing results. The computer could communicate with some modules, but not with others. We also found apparent aftermarket components and repairs in the electrical system/security system.

It appears that the wiring system is wearing out and developing faults. At 250,000 miles, I don't think I will keep pouring time or money into this vehicle. I will probably sell it as a non-working vehicle and move on.

Sorry for the sad report!

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Sunday, October 29th, 2023 AT 12:00 PM

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

You might want to send out the PCM as well, also was this car in a flood? Here is the location of the PCM so you can send it in as well. Thanks for getting back to us. Check out the images (below).

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