Car Gurus Please Chime In

[Moe Ron]

I have a 2004 GTO. Got some electrical gremlins. I get messages on the dash.
1. ABS fault. System fault contact dealer
2. Airbag fault. System fault contact dealer
3. Fuel gauge fault. System fault contact dealer
Also A/C quits working while this is happening.
Problem comes and goes. CEL doesn’t come on and car runs fine. Same messages every time.
Done online research and talked to some knowledgeable buddies. Thinking bad BCM. These cars have an issue with the BCM harness rubbing on a metal bracket behind glovebox. There was some chafing there. A few wires had insulation worn down to bare wire. I taped them up, got the harness away from the bracket but no luck.
Any input appreciated.

 

[Bryan W M]

Depending on what the computer wants to see if the wire had any damage it could still be the problem.
I work on John Deere we have had a tractor that just one broken strand in the wire was enough to cause a problem.

 

[Threadcutter308]

I'm not a professional mechanic, nor do I own a GTO. I have had Suburbans and Denali's. I have had some of those same types of faults and the solution was to clean (or replace) the MAF (Mass Airflow Sensor). Get the CRC brand from your local auto parts store, read the instructions and perform the cleaning procedure. It's simple, just don't use the wrong chemicals.
I can't say that that will make all your problems go away, but could help with some of them. Beyond that, a pro mechanic should get involved.
You can get a Scan tool, but the less expensive one's don't go as deep into the parameters and fault codes as the Profe$$ional ones. The less expensive ones are a bit of a pain because you think you "don't" have a fault, but the scan tool is just not annunciating it.

 

[Moe Ron]

I’ve got a “scanner” just your basic code reader as you say. Thinking of getting a more sophisticated one. The Autel MX 808. They’re $300 and change. Also I found a used BCM on Amazon $45 I violated my Amazon boycott. I’m so weak. Couldn’t pass it up. Even if it’s junk. Ain’t out that much.

 

[mtlucas0311]

I’ll say up front that I’m much more knowledgeable about Chrysler/Jeep than GM, but the diagnostic approach is generally the same. In my opinion the worst thing you can do when you have a problem like yours is to start winging modules at it. You’re just guessing, and that gets expensive fast. The first thing I would try to figure out is if these problems are related or unrelated. Did they all initially occur at the same time, or did one happen first and then the others later? If they happened at the same time, then the issue likely lies where these systems all intersect, usually a large body connector, etc. If not, you‘ll want to connect to the vehicle and look at what codes you have and address each problem individually.

 

[Kickin45]

Thread cutter bit it on the head.
MAF sensor.
My Astro, Tahoe and Syclone all had MAF sensor. It’s a major problem causer

 

[Moe Ron]

Thanks all. I’ve been thinking MAF sensor too. I’ve been getting Lean Bank 1&2 codes for a while now. Replaced O2s, checked vacuum leaks, cleaned MAF. Frustrating. I should take it to somebody. Nah
The other problems did all start at the same time. I’ll do some electrical troubleshooting on that MAF.

 

[Mike Casselton]

Also, disconnect and properly clean your battery contacts and cable ends. That can cause a ton of issues with GM vehicles.

When you remove and clean your MAS, make sure it's completely, and I do mean completely dry before you reinstall it or you'll destroy it.

 

[Threadcutter308]

Thread cutter bit it on the head.
MAF sensor.
My Astro, Tahoe and Syclone all had MAF sensor. It’s a major problem causer

I haven't had 100% luck with that (for all problems under the sun) and I don't want anyone thinking I'm promoting it as a cure all. But, I HAVE had enough luck with it to cause me to wonder if it isn't a "well respected revenue stream" on the part of Dealers who have unsuspecting customers come in for "much bigger problems".

I'll never forget (it's been almost 20 years ago now) when a co-worker told me that his diesel Jetta (I think it was a Jetta) had no power and was getting progressively worse. He told me he had taken it to a dealer for diagnosis and was told that it needed a new throttle body . They quoted him $850.00. I told him to go buy a bottle of SeaFoam, block out a couple of hours on Saturday, I'd come over and we'd fix (clean) it. He wasn't comfortable with that and took it in to the dealer, $850.00 later.

I actually now have a couple of good independant shops that I deal with. They aren't cheap, but they are fair and I trust them. That's why I don't do much of my own work anymore. The older I get, the more my time is worth (to not work on cars).

 

[Threadcutter308]

Also, disconnect and properly clean your battery contacts and cable ends. That can cause a ton of issues with GM vehicles.

When you remove and clean your MAS, make sure it's completely, and I do mean completely dry before you reinstall it or you'll destroy it.

And..........don't succumb to the temptation to stick your finger into the unit. There are wires (platinum, I think) spanning the interior that are so small, you can't see them unless you are looking for them.

The other thing that I have done is to simply replace the MAF and not screw around with cleaning. Cleaning is simple, but let's say you have 100K on the vehicle/MAF. A can of cleaner is $10-$12 and a replacement MAF is ~$50.00. There is more labor involved in cleaning than replacement. Is $50.00 really that expensive ?

Oh, and stay as far away from Autozone parts, particularly their branded parts as possible. Pure junk. For my Chev and GMC vehicles, I buy Delco/OEM parts. I don't know anything about Pontiac/MoPar parts, but if they have a good Rep, buy them.

 

[nockhunter]

Bad ground has caused a bunch of problems for me. On my dodge dakota the ground under my airbox was corroded and it took a long time before I figured that one out.

Good luck
Mike

 

[BullGear]

Bad ground has caused a bunch of problems for me. On my dodge dakota the ground under my airbox was corroded and it took a long time before I figured that one out.

Good luck
Mike

Yes, it's probably a bad ground or corrosion which has broken a ground wire. The only problem with this is there are 1000 grounds on modern day cars.

Good Luck!

 

[Moe Ron]

Thanks gentlemen

 

[JMGlasgow]

Most likely a bad ground or a wire shorting to ground.

The MAF sensor has absolutely nothing to do with ABS, SRS, or fuel gauge. Completely different circuits and control modules. The engine would also run like complete shit if the MAF sensor had a problem.

 

[songdogslayer]

Most likely a bad ground or a wire shorting to ground.

The MAF sensor has absolutely nothing to do with ABS, SRS, or fuel gauge. Completely different circuits and control modules. The engine would also run like complete shit if the MAF sensor had a problem.

This right here, you’ll need a tech2 scanner to read body codes. Cheap Obd2 reader will only read ecm and some Tcm codes not body codes

 

[Moe Ron]

I’m wondering if the wires of the BCM harness that went to ground on the bracket fried sompin’ in the BCM. I’ll figure it out or I won’t

Thanks

 

[songdogslayer]

If it’s intermittent I would suspect a bad wire or a module interrupting the can bus signal

 

[Tims]

Look here. https://www.gtoforum.com/threads/fuel-gauge-error-abs-fault-airbag-fault.95722/
FWIW Im not a Tech.

 

[whatsupdoc]

Get a wiring diagram for you car and see if the maf sensor, abs, airbag wiring share a common connector, common ground.

 

[S197]

I have a 2004 GTO. Got some electrical gremlins. I get messages on the dash.
1. ABS fault. System fault contact dealer
2. Airbag fault. System fault contact dealer
3. Fuel gauge fault. System fault contact dealer
Also A/C quits working while this is happening.
Problem comes and goes. CEL doesn’t come on and car runs fine. Same messages every time.
Done online research and talked to some knowledgeable buddies. Thinking bad BCM. These cars have an issue with the BCM harness rubbing on a metal bracket behind glovebox. There was some chafing there. A few wires had insulation worn down to bare wire. I taped them up, got the harness away from the bracket but no luck.
Any input appreciated.

check to see if the gauge cluster had been updated to the most recent version. then I would look at replacing the BCM.

 

[fastgun]

I had a 06 GTO same thing it was a bad BCM

 

[z28kid]

I think the ground that may cause some of those issues in on the passenger side cylinder head.

Have you replaced or made any repairs before you started seeing these issues? For example: new radio or speakers, installed aftermarket headlights (HID), replaced air filter, or even had it serviced?

 

[The D]

Why are you messing around with the maf sensor? Is there a separate driveability problem? If not, that has zero in common with the rest of the problems if the cel isn’t on

It sounds like you should pull the glovebox and check the wiring that is a known issue. If that doesn’t work, get the most detailed wiring diagram you can find and check for anything common to all those systems. Grounds, connectors on bcm, relays, shit like that

 

[The D]

Also, how is the alternator and battery? Either of these things starting to fail can do some weird shit