stone4779

iTrader: (2)

OK I been working on this truck. Truck ovbiously hasnt been cared for.

Anyways...Guy called me and the truck wouldnt stay running, barely made it to my house.

Got DTC P1637 (Alternator "L" terminal circuit)

Figured it had a bad ground...found that the grounding strap that goes onto the Alternator bracket was missing...tested the alternator just to be sure...it was fine.

Fixed that, then the truck wouldnt stay running still...figured the plugs got fouled from not having enough spark. Changed those.

Snapped off the rear spark plug on the drivers side, ceramic and nut came off, leaving the threads and the arm inside the cylinder head. Guy said he owned it for two years, never changed them. OMG.

Anyways, I used a tool I got from AutoZone to remove it...

Truck fired right up. Ran awesome. Drove it around for a couple hours, let it idle for a while, mized it up a bit. Turned it off, on, off, on let it sit etc etc just trying to replicate day to day driving.

Called the guy to pick it up, he shows up, Im in the driveway(with it running) and I decide to turn it off and try to crank it ONE MORE time to make sure and it just cranks over, wont stay running. Im like WTF?

So I find the blown fuse (ECM B fuse...20A btw) and replace it...turn key forward let it sit...the fuse doesnt blow. Once I tried cranking it, the fuse blows.

We blew about 7 fuses trying different things.

I found that the front door speakers were aftermarket and install poorly. The wires leading to them were not shielded and were directly touching the door frame. Both the positive and negative. On both sides.

I shielded the wires, used my multimeter to try and find any more shorts, couldnt find any.

Tried starting it with a new fuse...same thing.

So now I am think...is the computer fried?

I disconnected the computer from the harness, replaced the fuse again, and cranked it a few times. It did NOT blow the fuse.

So at this point I am assuming that the speaker wires shorted out to the foor frame, and maybe somehow fried the PCM.

What do you guys think?

He is supposed to go get a remanufactures PCM ordered tomorrow. They have it at the wharehouse in the next town over, so he might have it tomorrow if not Monday.

Any help would be highly appreciated.

THANKS!

-Chris

stone4779

iTrader: (2)

BTW also got P0137 and P0157, wires are fine, thinking that the cats are clogged due to all that fuel not being burnt and dumped into the exhaust. Truck stumbled on the low rpms a bit after I finally got it running for that short time. Totally unrelated Im sure but figured I would post it anyways...

As you can tell this truck has a few gremlins lol

stone4779

iTrader: (2)

Sooo....no ideas anyone??

I just put a new PCM in it just now and the battery is low. Is stumbled EVER so slightly for about 1-2 seconds then the battery died.

Can you fould the plugs just from cranking it a few times with no spark?

I just replaced them lol.

Anyways....I am charging the battery right now so I will try to start it again here in a few minutes...hopefully she runs!

pdsq98gt

You either have a bad PCM (which I doubt), or you have one of 2 shorted wires from the fuse block to the pcm. I would take off the large outside plastic side cover off of the fuse block and check for a mouse nest. If there isn't a nest there. unplug the pcm and check for continuity to ground on the ecmB fuse, you should not have continuity to ground with the pcm unplugged. The wires just run a couple of feet from the UBEC to the PCM, if there was a short there you should be able to see the harness rubbed through.