V1 Gremlins - multiple symptoms SOLVED

[escapepilot]

Thought I had everything finally dialed in but an intermittent gremlin has popped up.

First symptom- no crank. Push and dump clutch = runs fine
Newly discovered symptoms - key in run position but no info in DIC (just dashes), fuel gauge = empty, turn signals don’t work

key in run position, lights work with switch, fuel pump primes, throttle opens, horn works, tach and speed rest at zero.
Key to crank = can hear feel all relevant relays click

I have checked continuity on the high speed data wires between Obd port to power steering module, ps module to bcm, and bcm to ecm = all good. OBD to PCM high speed data continuity = good. Low speed data from OBD to each module and IPC = good.
I have checked all fuses and swapped relays around, verified all plugs are seated.

Ideas?

SOLVED - Bad ECM. Wasn't reliably sending signal to ECM for crank.

 

[Gtstorey]

Loose connection somewhere, but too many possibilities to speculate. And could be more than 1 causing the different symptoms. I fought this off and on for about a year. Fixed the fuse box end by removing the individual wires from the plugs and tightened the connections. Bcm has an additional bracket over one of the connectors to hold it in place. I could stomp on the plate over the bcm to make it start working.

 

[escapepilot]

I’ve not been able to find any loose connection or anything. I did notice that the vats light never comes on. I did verify the light itself works. Don’t know if it’s related.

So many issues and the only thing in common is the bcm. Going to do some more testing of it tomorrow. The bcm power fuses are good but I’ll verify that it is getting voltage to all of the proper terminals.

 

[Joebob]

I had a lot of issues that stemmed from loose pins in the connectors to the BCM. Check there before trying to find a new BCM. Remember we messed with a lot of wires and messed with the connectors a number of times on a 15+ year old wiring system.

 

[Andrew Barry]

Are you sure the starter is getting signal at the s terminal?

 

[Gtstorey]

It’s not getting power at the s terminal or it would turn over.
The loose connections can be hard to find since it can be an individual wire in a bundle and it might not move much when the bundle moves. Very doubtful it’s a bad module.

 

[LLBenJ]

I recently had a "car stopped dead in middle of road" event. it was a loose ground. That particular ground won't be a problem...ever. DF completed my wiring and I have 3 ground points on the car. Have you checked those? I bring them up as I had dash/partial power when the car quite. We pushed the car back home (lucky, 1 block away) and I started with the big stuff from a power perspective. Ground leading to fuse box/PCM was loose and computer said "nope". Traveling over a bump and a fraction of a MM in a loose connection caused this. Easy to check these and rule them out.

 

[Keckster]

Yup I would check all grounds and power wires at the bcm, Especially the plug on the back the goes against the front bulkhead. I've helped with two separate goblins with this issue and both had a mistakenly clipped ground. On my personal goblin I had a power wire pinch behind the bcm when it was mounted causing an intermittent no start with zero lights on the dash.

 

[escapepilot]

No smoking gun yet.
Grounds checked, plugs and pins checked, low and high speed data checked, power to all pins that get power.

if it goes through the bcm, it isn’t working (no crank, no DIC, no turn signal). If it doesn’t go through bcm, it seems to be ok (horn, lights, fuel pump, brake lights).

I also am not seeing the anti-theft symbol on the dash light up at all. Verified that the led works, but it never lights up. Can’t recall if it did before.

I just had the mileage reset to actual Goblin miles. Drove it about one mile around the area to verify odometer was working then parked it. Next day, is when the problems started. I feel like I’ve eliminated all possible problems except bcm and vats. I don’t know of a way to check either one without specialized equipment.

 

[Gtstorey]

Have you used a scanner that can read more than the ECM modules? It might tell you something. Is the BCM getting power on all the circuits that feed it?

I still think it’s a lose connection that showed up because you had the BCM out.

 

[escapepilot]

Have you used a scanner that can read more than the ECM modules? It might tell you something. Is the BCM getting power on all the circuits that feed it?

I still think it’s a lose connection that showed up because you had the BCM out.

You are probably correct. I thought of something late last night that I wanted to try. I removed the crank relay and jumped the line side to 12V direct (simulate the relay closing) and was able to crank the car and let it run briefly. I shut it off quick because I was in the garage (door open) and needed to leave for work. Thought about it a second and started it again and remembered to look at the DIC which was now working properly. However, when I shut it off and the lights stay on a few seconds with RAP, the lights flickered multiple times. So, SOMEWHERE there is a loose/broken connection. I'm thinking it might be at the fuse box because that is where I was working this morning and the only thing in the front that was touched was the key. Unfortunately, I could not duplicate everything working before having to leave.

Is it possible a bad connection in the VATS system could cause this issue? Only considering it because of not getting the anti-theft symbol to light up on the cluster. I'd like to eliminate that as a source of issues.

Since everything else seems to check out, I'm going to open up the fuse box again and verify all of the connectors are making good contact.

 

[Robinjo]

Is it possible a bad connection in the VATS system could cause this issue? Only considering it because of not getting the anti-theft symbol to light up on the cluster. I'd like to eliminate that as a source of issues.

Since everything else seems to check out, I'm going to open up the fuse box again and verify all of the connectors are making good contact.

Do you have the HP Tuners? Just turn VATS off in that?

 

[Gtstorey]

I don’t think the vats system has a direct connection to the vats light but I don’t know that for sure. I think it reports to the other modules to turn it on. But I’m not sure. You need to study the wiring diagram to see.

 

[Gtstorey]

And my understanding of vats is that it basically causes things like not send a crank signal and the fuel pump to not work. It would not cause issues with displaying data and all of the modules still talk and function.

 

[escapepilot]

Update time! It’s getting stranger and it’s currently running.

So this morning, I decided to bypass the bcm and relays and try to start by turning the key to run and then applying 12v to the purple starter trigger wire. It started and I shut it off with the key. Started it again in the same manner to check the DIC and the turn signals. Both worked!…but then the lights started to blink on/off like a bad connection then completely off.

After work, was going to verify power at every connector in the start circuit. Before I did anything, I was trying to verify which PMC connector is which. Turned the key to run and everything came on like it was supposed to…but then started the blinking like a loose connection again. This time, it stopped with everything on. I cannot duplicate the problem now. I’m inclined to think the loose connection is either in the PCM connector or in the fuse box connectors.

Additional mystery…my odometer reset to zero. Not trip meter, odometer! How in the??? Also, when I move the light switch to high beams, the lights go out. When I try the flash to pass with the key on, they go out and come back on when released. If I turn the key OFF and flash to pass, the lights come on.

Somewhere, all of these issues are related. Where? ‍I dunno

 

[Gtstorey]

Following based upon later model wiring.

low beams work by directly grounding the low beam relay by the switch. High beam works by a ground signal to the bcm which in turns ground high beam relay. About the only thing they have in common is the switch and the headlight ground. You need to track down what is actually grounding and getting voltage when you switch the lights. You need to use the diagram for your model but the function is probably the same.

 

[Keckster]

Have you messed with the metal post that stick out the top of the fuse box. Mine was loose and had corrosion under it causing a flickering condition like you mentioned

 

[escapepilot]

I think I have narrowed it down to…..a ground. When checking individual grounds at the connector end, I found one that is showing open. All I can find is that it is fuse box connector C1 pin F3 circuit 150. I can’t find that on any schematic though. Anyone know what circuit that goes to? I made a list of all grounds in the connectors and am verifying they are good but we did thin out some unused grounds such as A/C grounds so I’d like to be sure this is a relevant ground before stripping off tape to trace it.

 

[Gtstorey]

Cut it, splice on a wire and ground it if it’s a black wire. Then you can see if it fixes your problem.

 

[Ross]

I agree with Gtstorey, just ground it.

I did find it in AllDataDIY.
I see the fuse box connector C1 you mentioned... pin F3 circuit 150.
Found circuit 150 in the fuse box here for wiper 1 and wiper 2 relays.

Then looked up the wiper electrical circuit here.

So it is a ground used multiple places in the wiper circuit. Maybe more places... I didn't scour the entire fuse box.