PCM Fuse Blowing

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TCSBuilds

Member
Hi all,

I've run into a bit of an issue with my goblin and need some help identifying a potential culprit. I've recently gotten my goblin back from a shady mechanic and it is no longer running. Long story short, the 20A PCM fuse blows every time on an attempted start. I'm not sure what was done to the car inbetween, but I do not have the funding to pursue any legal action on the shop or have the car sent to another shop to have someone else figure it out.

I've gotten it towed back to the house, however the wiring was done by Lonny so I'm not exactly sure where to start with the troubleshooting. I've tried a larger 30A fuse and that also blows on an attempted start. I have a spare PCM but I'm not sure if "plug n play" is an option here since the fuse is blowing no matter what size. I'm guessing something somewhere isn't grounded properly or I've got a connection that may be unplugged/loose but I'm not sure where to check.

Any ideas?

I'm also hearing three clicks from the fuse box area when I turn the ignition off but it doesn't occur every time. Unsure if it's related or not.
 
Desert Sasqwatch

Desert Sasqwatch

Bigfoot Goblin
What did the offending shop do to your Goblin? You have courses of action you can pursue that involve minimal cost. Contact the Better Business Bureau (complaint and putting the business on the 'avoid' list), the Society of Automotive Engineers (certification can get pulled), and a local TV station who likes to televise stories like this one (and could be a piece about the Goblin and your hard work to build it). Don't give up and give in to hacks like this business. You and other victims don't deserve this kind of shody workmanship.
 
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Gtstorey

Goblin Guru
Donor?
This is lo likely damaged wire between the fuse and the PCM. Hopefully they didn’t do anything to the PCM eternally. This would be hard to do. As DS asked, what was the mechanic attempting to do? What area of the car was he working?
 
T

TCSBuilds

Member
Gtstorey said:
Donor?
This is lo likely damaged wire between the fuse and the PCM. Hopefully they didn’t do anything to the PCM eternally. This would be hard to do. As DS asked, what was the mechanic attempting to do? What area of the car was he working?
Click to expand...
The car was brought in because I snapped one of the control arm bolts connecting to the subframe and for a final inspection prior to registration.

I drove the car into the shop April 5. I got a call that everything was good to go last Friday. The next day I received another call that the car is no longer starting and the PCM fuse is continuing to blow.

Our original agreement was to keep the car covered, and after visiting Monday and seeing the car was left unattended outdoors (cobwebs, bird crap, pollen, bugs etc.) I confronted them about it in which they stated the original work the car was brought in for was completed (bolt replacement and inspection) and being that it's a unique case (and my feelings towards them behind it) they no longer wanted to work on the vehicle or provide an inspection for a vehicle that is not running.

I understand this IS BS, but like I said, I don't have the funds to fight them in court, pay for lawyers, etc. I just want my car back and running again. I'm looking for any help in that regard.
 
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Gtstorey

Goblin Guru
I looked at your post history to see that you have turbo SS as donor.
There isn’t much distance between the fuse box and ECM so unless you see obvious damage to wiring, I’m not sure this is the fault of the shop that worked on unless it is water damage to the ECM or fuse box.
Wiring diagram is pretty simple for that circuit.
 

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Rttoys

Rttoys

Goblin Guru
Sounds like a hard short to ground somewhere

Where are you located ? See if anyone in the area can help.

Pics of car and some of the wiring?. Maybe one of us sees something.
 
Desert Sasqwatch

Desert Sasqwatch

Bigfoot Goblin
Welding was done to the car? Did they disconnect the battery before welding? Did weld spatter hit a power line to expose it and is now shorting to ground? Did someone tug on a wire harness and half pull wires out of the connector to create a short? I would be all over these chumps playing 20 questions how the car was operable when they took it in to work on it and they obviously and evidently F'd up something they were not supposed to - and record the entire conversation. Take photos of everything (you did get photos of the condition your Goblin was in when you went to pick it up?). You are being screwed over by this shop and they sound like they think they can do whatever they want, NOPE! Where are you located, you do not have a signature with your post?
 
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Gtstorey

Goblin Guru
Coincidences do happen. Especially when vehicles sit. I would diagnose the problem before placing blame. This isn’t a factory built car that you can say it was running when I brought it in, therefore any problem must be something they caused. Unless you can see damage in the area of the work they were supposed to be in, it would be hard to do this working on the subframe/control arm.
Which side were they working on?
 
T

TCSBuilds

Member
I'm in Conroe, TX, just outside of Houston.. I understand coincidences do happen, however, I'm attempting to diagnose ALL the problems and this is currently at the top of the list. The car also seems to be stuck in gear, I believe the passenger side axel is broken but I was told that "that's play in the inner joints" and I've gotta check which connectors were unplugged/removed during whatever testing they were attempting to do. I truly believe someone launched it, snapped the axel and in an attempt to fix it, messed something up electrical. I've asked countless questions and gotten very little detail in return. I'm unsure if any welding was done to remove the subframe bolt I broke, but that's all that was supposed to be done to the car and the problem was on the opposite side of the car from the fusebox. I'm just thankful to have the car back in one piece and it wasn't' stripped down or dogged out any worse.

It just sucks that instead of being able to finally (legally) drive her this summer, she's going back into the garage for who knows how long
 
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Gtstorey

Goblin Guru
Start with unplugging the X2 connector from the ECM and see if it still shoots the fuse. And no more putting in a 30amp fuse to see what happens. You could smoke the entire wiring harness. If anything put in a smaller fuse to test with. And it looks like it should be 15Amp fuse to start with if this is actually the PCM/ECM fuse.
 
T

TCSBuilds

Member
Gtstorey said:
Start with unplugging the X2 connector from the ECM and see if it still shoots the fuse. And no more putting in a 30amp fuse to see what happens. You could smoke the entire wiring harness. If anything put in a smaller fuse to test with. And it looks like it should be 15Amp fuse to start with if this is actually the PCM/ECM fuse.
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My fuse box says it's a 20A on the inside lid and not a 15A. I had that argument with them as well after they told me someone put in a larger fuse to band-aid a PCM problem and I had "Faulty wiring". I'll try disconnecting the PCM and see if it still pops the 20A fuse.
 
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Gtstorey

Goblin Guru
I would still go with the smaller fuse. My service manual is actually for a 2010, but I don't see any reason that the 2009 ECM will pull more amperage.
 
Rttoys

Rttoys

Goblin Guru
You are somewhat local to the Houston group (I’m in Waller). I can come by sometime to take a look. Can’t promise anything, but maybe we can get a good direction to go in.
 
T

TCSBuilds

Member
Gtstorey said:
Start with unplugging the X2 connector from the ECM and see if it still shoots the fuse. And no more putting in a 30amp fuse to see what happens. You could smoke the entire wiring harness. If anything put in a smaller fuse to test with. And it looks like it should be 15Amp fuse to start with if this is actually the PCM/ECM fuse.
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Disconnected the x2 connectors from the PCM and the 20A stays in tact when attempting to start. Noticed one of the pins (top right) looks off but that's the only oddity I can see when investigating. No other pins on the PCM appear to be bent.
47687
 
Rauq

Rauq

Goblin Guru
Below, 1, 2, and 4 should have continuity to ground, and 3, 5, and 6 should have continuity to the 15a PCM fuse. Can you verify continuity for each, and verify that the grounds don't have continuity to the ignition fuse and vice versa?

When you say it smokes the PCM fuse on an attempted start, does that mean that the fuse is fine if you just turn the key to on and don't try to start it?
47688
 
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Gtstorey

Goblin Guru
This is starting to sound like a damaged ECM. It's probably not 100% impossible something downstream of the ECM is shorted but, most of those circuits are pretty protected from overload by the ECM.

I would try and see if you can get it to shoot the fuse with x2 disconnected and ignition on by wiggling the wire a bunch just to confirm that there isn't hidden damage to the wiring harness that is intermittingly shorting to ground.
 
T

TCSBuilds

Member
I have a spare PCM/ECU that I picked up a few days ago but I'm afraid to plug it in, fearing there may be something in the line that may have damaged the original. I'll see if I can get it to pop the fuse without the PCM connected but if not, I'm not sure what's needed to swap the spare over. I'll double check the wiring to make sure nothing is damaged
 
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Gtstorey

Goblin Guru
I might even unwrap the harness from the X2 connector to the fuse block for a visual inspection, but I don't remember the actual routing to see how much work this is.

Before replacing the ECM I would try and visually inspect as much of the entire wiring harness that I can for damage. But again, the ECM does a pretty good job of protecting itself from downstream overloads.
 
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