I posted on Monday thinking I had fuel problems... now I'm pretty sure it's electrical and I don't have a clue where to start looking.

Symptoms:
While running at highway speed, power just suddenly dies... like the ignition is turned off. No sputtering, just flip a switch suddenly no power... truck is coasting and driving the engine. Wait to Start light comes on. After a fraction of a second, it usually runs again... but might cut out several times in quick succession. It seems like quickly getting all the way off the throttle then back on helps it restart.

If truck is coasting at low rpms or idle, engine will usually die. Have to stop and restart.

Restarts often take multiple attempts and sometimes several minutes... either won't fire or will run a couple of seconds and die. Usually have to start with parking brake off because releasing the parking brake usually kills the engine. Also usually have to get RPMs up a bit before shifting into Drive, because the engine will either die or lope badly. The loping is idle to maybe 1200 rpm about once a second, and I have to drop it into neutral... and the engine usually dies.

Symptoms appear to be worse and more frequent after the truck warms up, and it almost always behaves badly coming to idle after a run at highway speeds. Check Engine light sometimes comes on but doesn't stay on, and rarely the other caution lights come on like a pre-start bulb check.

I did notice tonight on the first start that glow plugs cycled on and off a bunch of times before staying off. I've never seen that happen before; voltage usually stays down a while then comes back up and stays up. And after limping home after a test drive, parking, raising the hood and the engine dying, the glow plugs cycled repeatedly... could hear the solenoid cycle a couple of times a second. And before I got out of the truck to pop the hood, the speedometer was chattering wildly between zero and 30 or so for a couple of seconds... while stopped.

On this evening's test drive, I don't think the engine was running quite right when it was behaving... like maybe the timing was off a bit.

I do have a Banks transmission chip and engine chip... the transmission chip has been for a couple of months with no issues and the engine chip for about two weeks with no issues.

I replaced the camshaft position sensor last night, and I see no change in behavior.

I'm thinking I've got a short or bad connection somewhere, but don't have a clue where to start. If I don't get any likely suspects, I'll start by pulling the engine chip.

Anyone want to point fingers at likely places to start?

 

Take the chip out and try it. Could be coming loose

 

Check engine oil level as well.

 

I think if your parking brake effects it then you probably do have a loose wire for the PCM, maybe a burned connection or something or the chip is loose if it's one that's installed in the PCM. It's right there by the brake pedal so that's where I'd start looking. I hate electrical problems myself. On newer cars I lost a lot of hair over them trying to figure it out. I quit my last job over a VW jetta that I just absolutely knew had a bad ignition coil. I put a new one in it and still no start. I was so certain it was just the coil that I ordered another one. Still no start. Then another one. No start! I went home early that day and said I wasn't coming back.

Then I called a guy at the VW dealer to talk about it and he told me the aftermarket coils wouldn't work and that he had a spare one in his tool box made by VW for testing. He met me at the shop that night and we tried it and the darn car fired right up. I was so mad I almost shot the car. I really wanted to.

When my boss called begging me to come back I told him he had to give me a raise if he wanted that car fixed and he agreed. Then I ordered a new coil from VW and had it running in 10 minutes. I was still mad though.

 

I didn't catch the parking part but the pcm wiring is on the other side of the firewall from the parking brake. BUT the parking brake could be wiggling a loose chip. Remove the chip and see what happens

 

Im having the same sort of problem. Mine i believe is the wiring harness where it plugs into the valve covers. The wires one one had melted together so i replaced the end all was good after that, now its starting again im going to have to break-down and buy a new wiring harness all together.

 

The Banks chip does piggyback onto the PCM board... so that's the first thing I'll be checking.

Will probably remove chip and run it for a while to see that I don't have other issues, then put chip back on... after cleaning all connections. Might take me a couple of evenings before I get everything checked, but I'll let folks know the results.

When I read TJ's thought on loose chip, I thought "D'oh!!!". That would explain why releasing the parking brake kills the engine.

The last thing I had changed on the truck was using about 15% biodiesel, and the fuel filter was rather gross, so I suspected fuel system blockage.

 

Make sure the truck keys are in the house if you mess with the chip...

 

 

The Banks chip piggybacks onto the PCM board, onto the edge connector on the top rear of the board. The chip hangs out the back of the case but isn't restrained by or touching the case, so it's basically hanging free off the edge connector. I pulled the PCM, and it had slipped off enough to be very loose and flopping side to side.

Pulled the chip off, cleaned the connections on both sides, let everything dry, reassembled, applied liquid electrical tape where the chip case almost met the module case to help hold everything together, and wrapped tape from one side of the module case over the back of the chip case, and down the other side of the module case... several times.

Took a test drive last night, no issues, and put about 130 miles on it today, again no issues.

Looks like the whole problem was the aftermarket chip coming loose. I owe some folks for the idea to check that. Getting the PCM in and out is really tight, and I may have bumped the chip loose on initial installation. This time, I removed the relay holder from the engine fuse block to get more clearance for the PCM.

Heading back out to West Virginia on Friday for some more kayaking, so the fix will get a good testing. And I'll have the tools to pull the PCM again just in case...

 

glad to see its running good for you

 

two words...DUCT TAPE!!

Glad it was an easy fix for you!

 

Or for the really big jobs.......GORILLA TAPE

Rog