Major electrical issue on the GTO.

NYSpeed Automotive
1

Posted over at LS1GTO.com as well but figured I’d give it a shot here too since there are some pretty good mechanics on here. Below is what I posted on the gto board. The only thing I really need to explain is the “dreaded key locked” thing. The lock cylinder has a little ramp that a pin rides up that GM used far too soft of a metal. A notch wears in it and eventually the key won’t turn at all. You pop the cylinder out, dremel out the notch, and everything is great. It’s about a 30 minute repair. On to my post…

First off, sorry for the long read but this is odd and having all the info might help someone.

05 M6 with 22k miles, stock other than brakes, axleback, LSS, skip shift eliminator and aux in mod to stereo.

A few weeks ago I got the dreaded key locked problem. Luckily a few times removing and inserting the key got it to turn and I got the car home and was able to do the cylinder mod. I drove the car that weekend a few times and everything was great.

I got in the car Monday morning and when I turned the key it wouldn’t start. The lights on my dash were going crazy, ABS and TC flashing, buzzing from a relay. At one point the car even turned over and started with the key just in the on position, not turned to start. Once started ABS and TC errors were on, the tach was jumping around between 2000 and 2500 despite the engine idling normally. Basically everything electrical was fucked.

I shut the car off and checked the battery, 12.2 volts. Battery connections good. Took the steering column apart, popped the cylinder out, everything looked fine. Made sure the security reader was lined up properly and put it back together. It still wouldn’t start, same jumpy electrical. Put some jumper cables on it, same problem. Then all of a sudden everything stopped and the car started perfectly.

Scanned with my OBD reader, no codes. Went to autozone and the battery tested fine, as did the charging system. Beat the piss out of the car for a little bit thinking if it was a short I’d recreate it, nothing. I drove the car for a week (it’s my daily driver) without issue until this morning.

This morning I open up the garage door and hit the unlock button and I hear the same clicking/buzzing relays. I look in before I even open the door and I can see the blue high beam indicator coming on and off. Then my trunk popped and I could hear my door locks unlocking multiple times. It won’t even try to start when turning the key. No click from the starter solenoid. Again the battery is at 12.2. I disconnected the battery and waited a bit and reconnected it. Still no go, still crazy dash lights. The check engine light was staying on even with the key out so I grabbed my reader but it wouldn’t even initiate a read. Turned the key to on and got 4 codes, 2 current 2 pending, all “N/A” with no code number. Then while I was sitting there with the key turned to on it was like the whole car rebooted. Gauges went back to normal, check engine light went out, and the car fired right up just like nothing had happened. Shut it off, started it, removed the key several times and it’s fine again. I even drove it to work today just to chance fate. Maybe it will get me home tonight, maybe it’s time to accidentally leave a lit cigarette in it and collect insurance. http://www.ls1gto.com/forums/images/smilies/smile.gif

I have no idea where to even start with this. I want to think it’s ignition related since it never happened until I took that apart. The only problem I had fixing the ignition though was when I first tried to put it back together the steering column lock had engaged and I couldn’t get the cylinder to go all the way back in. I pushed a bit on it and tapped it a few times but never put much force on it since the directions said it should slide right in. Shortly after I figured out how to push the lock back into place with a screwdriver and had it back together and it started fine. There are no stored codes now and I know if I take it to the dealer they’re going to give me the old, “the car is working fine now, couldn’t find any problems”.

EDIT: Battery is new as of 1.5 years ago. Quality Napa battery.

2

Wow that sounds crazy. Good luck man, electrical gremilins are never fun.

3

anything warranty can cover?

4

yikes.

you should have bought a honda

5

Sounds like German engineering

6

fixed

7

My money’s on a control module giving up the ghost, and it just being coincidence that it happened when you hacked your ignition. Something this nonsensical’s gotta be a computer issue.

BCM Maybe?

  1. I know jack doodle about the VATS module, though it is refered to often here in the hybrid section.

  2. I am staying out of trouble here.

A: I really don’t want a ‘warning’ PM from the mods or www.helminc.com for ripping off the manual without permission.

B: the 04 GTO PCM has two 80pin connectors on it and I really don’t feel like typing all that in.

  1. To the best of my general knowledge:

A: The 04 GTO uses LS1 standard class II serial data and standard LS1 PCM architecture under the hood.

B: There is ONE PCM for both the A4 and M6 2004 GTO. I believe there are some software differences inside the PCM between A4 and M6. The PCM knows a whole lot about what is going on inside the A4, and very little about what is going on inside the M6 gearbox. I did spend a few minutes looking for the A4 connector in my transmission tunnel while doing the !CAGS mod on my M6, could not locate the A4 connector.

C: general network architecture: imagine the BCM, body control module, as the padded cushion at the top of a three legged barstool.

  1. The tertiary serial data bus (first leg of barstool) connects the BCM to the airbag module. In event of a failed module to module handshake or failed BCM the airbag module, apparently from info in thread at ls1gto, can illuminate the airbag light in the IPC probably by supplying a ground directly to the IPC.

  2. Second leg of barstool is the secondary serial data bus, BCM to radio and IPC.

  3. Third leg of the barstool is the primary serial data bus. From the BCM, this data bus tags the OBDII connector, than on to the PIM (Powertrain Interface Module). The PIM translates UART serial data from the BCM and class II serial data from the PCM back and forth so the BCM and PCM can talk to each other. By extension the primary serial data bus in the car travels from the PIM to the PCM as classII rather than UART serial data.

  4. Poorly documented in the Helm’s manual is the ABS serial data bus. As drawn it connects the ECBM (electronic brake control module)and OBDII connector only.

  5. On the 2004 GTO, each of ClassII PCM serial data, UART primary serial bus data, and (protocol unknown) ABS serial data are directly available to a TechII scan tool at the OBDII connector.

Take home data:

  1. GTO specific parts already in Michigan take 2-3 weeks to my door step via Fred Beans or GMPD. GTO specific parts in Australia take 6-8 weeks to my door via the same distribution channels.

  2. If I was using a GTO powertrain as a donor in a hybrid, I personally would ditch every possible item of the GTO electronics. They are very expensive and a lot of them (IPC, BCM) are core exchange only.

Certainly you could transplant the entire computer network to get ABS brakes and the airbag system and the 6 disc CD changer, but you are commiting to a slow moving, high priced distribution channel to do it.

  1. I fully expect at least one of the vendors here can/could ship you a working engine/transmission PCM for 04 GTO LS1. If I was in that situation, knowing what I know about the 04 GTO electronics from owning one, I would pay $400 plus core, with the caveat I need closed loop on the cats and OBDII connectivity for the smog police in my state.
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well did you try starting the car with the cylinder removed? your code reader probably can’t read body module or chassis codes hence the n/a. Probably some sort of u1000 code. it’s either something in the column or a bad module. Thats my guess.

9

BCM?

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BCM controls everything in that car from a quick look @ the diagram, make sure the connectors aren’t unhappy, possible water intrusion ect?

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Went home for lunch and of course it starts just fine at work and at home to come back to work.

psychopjv, what do you mean “try starting the car with the cylinder removed”? With the cylinder removed how would I start the car? The cylinder holds the key. Even if I tried to manually turn it with a screwdriver or something the security key is going to prevent it from starting.

And yeah, I’m thinking BCM (body control module) but I’ve never seen a complicated computer like that work for weeks at a time and then flip out, then work, then flip out, then work again which is why I’m really confused. Usually when you “pop” a complicated unit like that they’re dead for good.

I scanned it again when I got home and there are still 4 codes, 2 faults 2 pending even though the check engine light isn’t on. I guess I’ll start by taking it to the dealer and seeing if their code reader will pull more than “N/A” on those codes.

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I’m going to check that tonight, along with some wires near the BCM in the passengers footwell that I guess have a tendency to rub through their sheathing (found when searching for BCM problems on LS1gto.com).

13

if it’s like every other GM vehicle to remove the cylinder you must turn the key to the on position verifying it’s the proper key. then remove the cylinder and try starting it.

14

Sort of. You turn the key to on, press an allen key into a hole in the top, and the key/cylinder comes out together. You can then press a little spring loaded pin on the cylinder so the key “guts” can be pulled from it while still wrapped around the key. As long as you don’t take the key out of the lock mechanism while it’s out of the cylinder all the little key tabs stay in place.

Once this whole assembly is out though I don’t see any easy way to try starting it.

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Sort of. You turn the key to on, press an allen key into a hole in the top, and the key/cylinder comes out together. You can then press a little spring loaded pin on the cylinder so the key “guts” can be pulled from it while still wrapped around the key. As long as you don’t take the key out of the lock mechanism while it’s out of the cylinder all the little key tabs stay in place.

Once this whole assembly is out though I don’t see any easy way to try starting it.

This documents it real well.

16

these things always seem to lead to some sort of alarm system problem, sorry for posting a useless post but this shit takes a while to track down

17

Make sure no part of the serial bus is grounded or anything pulling parasitic power off it.
If you connected anything to the data bus wires (that may look like normal power wires)
things will freak out kind of like you described.

Check for pinched wires, damage, water, ect.
If all is well then replace BCM.

18

^maybe trade bcms with someone. (idk if anyone would volunteer to be stranded though if it is the bcm)

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FYI - I Posted in the other thread… won’t duplicate it here.

BCM’s are coded with the VIN - part of the radio theft thing. So if he doesn’t have his OEM security code, the radio won’t work with someone else’s BCM.

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for testing purposes I am sure the radio can be left off. lol