Alright, went over my AE again and noticed that just as the truck stalled, it lost FICM sync and then the ICP desired dropped off totally. The ICP desired didn't come back until FICM sync was re-established.

I've gone over the wiring again, found one slightly loose ground on one of the batteries & tightened that up. Checked the CMP & CKP sensors - did some wiggling of the wires and harnesses while connected with my multimeter to see if anything was triggered. When I was connected into the CMP sensor wiring it started at 835 ohms and went up to 852 as I wiggled the harness...not sure if that's a big deal or not??

I've also noticed that the cam & crank go in and out of sync, KOER.

After wiggling the harness and boosting the truck again, the check guages light came on and I got these codes:

P0098
P0118
P0198
P0470
P1000
P2285

2 minutes after start up the engine oil & coolant temps were well over 200F - which is obviously impossible - but the guages on the dash were not moving.

These are all connected via the engine harness connector to the PCM, right?

What is the normal operating temp for the this engine?

 

P0098 - Intake air temp sensor 2 circuit high (remember the codes from before...)
P0118 - Engine coolant temp circuit high input
P0198 - Engine oil temp circuit high input
P0470 - Backpressure sensor circuit error (EPB sensor on drivers side manifold)
P1000 - nothing to worry about, just says you didn't complete the drive test
P2285 - ICP sensor circuit low.

I'd be looking for another wiring harness myself, just to eliminate it.

 

yeah, that's what I'm leaning towards as well.
thanks.

 

I've taken almost the whole harness apart piece by piece and from what I can see there's no obvious issues with it.
Just before I did that I started the truck and it was running awful, chugging, belching bluish/white smoke like mad. I had a wooden stick that I was wiggling the harness with, and when I pressed in one spot where the harness was zip-tied up (not super snug, just keeping it off the engine) suddenly the tone of the engine changed, it ran smoother and WAY less smoke.
Would you say that's an indication of a bad harness? (stupid question maybe....)

I've put the harness back together and am planning to test all of the sensors again just to be sure.
Is this possibly the PCM?
I've also discovered that I have a bad battery. Big surprise.

I took it for a test drive tonight and lo and behold, it stalled. There were a few changes - the only code I have now is the P2285. Just as it died the ICP actual dropped to about 690 - it had been staying steady at 870 since the harness was put back together.

(EOT & ECT were good)

I boosted the truck for about 10 minutes and it restarted. I had also disconnected & reconnected the ICP. I drove it home with no problems…

 

Hey guys it's been a while but I have been working on the Excursion off and on for the last few months so i thought i would post an update and maybe get some suggestions. I repaired the electrical problems that were present; i had a code for the ICP circuit (P2285). I replaced the connector to the ICP sensor and the code went away. Took it for a drive and it stalled again; same code comes up. I got my hands on another PCM, just to try it, ended up with all kinds of running issues, and still had the P2285. I put my original PCM in and while doing that found the socket for the ICP signal wire pushed out of the connector. Pushed it in and made sure it was in properly, and checked the other sockets in the 3 PCM connectors. Reconnected everything and all codes gone. We also replaced the batteries at this time. We drove the truck for 3 or 4 days in town with no problems whatsoever. My wife went out of town and made it maybe 10kms and truck started surging and then died. Once again it wouldn't start. Got it towed home(approx 1/2 hr after it stalled) cranked for 10 - 15 sec's caught and died. Tried again and it ran fine. Hooked up AE and got codes P0299, B1359, P1000, P2285(we disconnected the ICP to see if it would start). When ever its running the ICP actual and desired are typically within 50 psi. The Ex runs great, nice and smooth after stalling. There was never any kind of significant smoke before it stalled or after. It didn't seem to get bad until after going over a set of tracks(these have been redone in the last year and are actually fairly smooth) and after getting up to highway speeds. I feel like i'm chasing my tail here. As soon as i fix one electrical problem another one shows up?????? Since then i have looked over everything but can't find anything. I drove it again and the same thing happened. This time though i went down some pretty rough roads at lower speeds 50 - 70 kph and there were no issues. As soon as i got to hiway speeds (right around torque lock up) it starts acting up and stalls. Now AE won't connect, it shows a message to check if ignition is on?? even when its running?? Also now the following codes are present - P0500, P0299, P1000 and B1483. I took a look at the recorded data from the last run and it looks like the ICP starts dropping to .4v and lower; the ICP actual drops off as well as the desired??? I'm getting a little fed up with this thing

Could these problems be the result of a bad ignition circuit? Maybe a poor connection in the switch that ends up shutting down the truck? When it stalls the dash still reads but its almost like when its in the run positions prior to start up. I don't really want to start swapping out harnesses until i can recreate the problem so i know what the proper repair will be.

Any advice anyone might have would be greatly appreciated.

2005Ex6.0

 

I would start looking at the fuse box and back of fuse box for bad connections, also where the harness comes out of firewall into engine bay, sounds like something is heating up and causing a bad connection and when it cools it is fine, pull all the connections that have plugs and look for heat damage.

 

Thanks bobfbigman, I'll do that.

Could this also be caused by a weak or failing relay? PCM relay?

2005Ex6.0