This has been going on for nearly a year now. The truck does not get driven a lot and even less since this issue started. It is not a miss. What happens, when it happens is that its like someone shut the key off and then right back on. It is split second. Almost like a CPS cut on a 7.3. I never have to restart it, it comes back all by itself. Also, when it happens, the cluster goes dead and comes right back (needles do not sweep), the WTS and WIF lights briefly illuminate. Also, the throttle goes dead for a split second and then takes a while to come back fully. Meaning: full throttle only feels like 50% or so. It gradually comes all the way back after about a mile or two. Its almost as if wherever the throttle was when the cut happens is the new 0% and it takes some 0-100%n applications of the throttle for it to relearn what true 0-100% is if that makes sense. When this happens, my CTS3 freezes and then goes blank and I have to tap the screen to wake it back up. Stereo does not cut out or reset. Also, no codes. I thought maybe it was an EBP sensor issue so I unplugged it and got no code with it unplugged. I figured that might be from the tuning so I tuned back to stock. Still no codes when the cut out happens. It is unpredictable and has happened at everything from light load to full throttle. Has never happened at idle.

Parts replaced chasing this issue: the pedal assembly - No change. I suspected a short somewhere on the 5V REF circuit so I replaced the engine harness with OEM - No change. Suspected EBP, drove with it unplugged for a day or so and had no issues, replaced it with OEM and plugged back in, cut out 5 miles later.

About the truck: CCSB 4wd late 2004 (first week of late 04). 127K miles. New shortblock, KDD Icon heads, FullForce 155/0, Powermax, BPD oil cooler with factory filter, ODawg manifold, BD exhaust manifolds, PPE uppipes and EGR cooler all at 109K. S&B intake, FICM tuned by ID Speed voltage runs 48.5-50.0. PCM tunes by ID speed. USA Diesel 185Amp alternator from Ed. New engine harness at 125K, New pedal assembly at 125K, New EBP at 125K.

 

Sounds like the PCM/Scanner lost power or ground


the pcm and obdII port share a ground circuit

some this you probably have checked the basics battery health cables clean tight

here is a wire diagram it’s only a start more would be helpful I don’t have access to my pc so my info will be limited

 

Is your only scan tool the CTS3? It is not the best at pulling ALL the codes.

 

I have access to several scan tools. I'll try AE and my SnapOn scanner tomorrow. I've been kicking around the PCM ground idea. I'll take a closer look tomorrow as well. My only thing on that is that I would think if the PCM is losing ground/power, I should get either a P0603 or P1000 or both. I could be wrong. I'll take a closer look. Thanks for the suggestions

 

2 power source to complicate things

PCM has to lose Keep Alive Power for code to set or gauge sweep

it also has Vehicle-Power that supplied upon turning key on that triggers the pcm relay and sends power to operate to pcm



either way could be power or ground issue or flakey pcm relay maybe bad pcm but that uncommon for pcm to be bad

 

You mention a flicker of lights on dash the glow plug flickers

You also mentioned the scanner would shut down and you would have to turn on again

so I looked for a common link between the two it was that ground to pcm and obdII port was shared but separate circuits for power to each
just something to consider

electrical issues create chaos so it’s hard to just say just change this or that complex testing might be required

im with you though the fact it didn’t set code does help narrow down things

I could be barking up wrong tree just going with symptoms dash light flicker and scanner going into standby mode

 

Just throwing it out there for what it’s worth. I run the Edge CTS3. My Edge is also obviously plugged into the OBD port. It would also shut off very intermittently while driving and I would have to touch the screen to wake it back up. No rhyme or reason to it, and was quite annoying. I started having gauge cluster related issues, where the gauges would go dead, no radio power, no power windows. The CTS3 would go dead when the gauges worked, and stayed powered up when the gauges cut out, so I didn’t think the two were related. I swapped the cluster with a rebuilt unit from Circuit Board Medics and obviously that fixed the gauge issues. I was not expecting it to fix the CTS3 shutting off, but magically it did. I don’t believe it’s a coincidence, but I have not dug in further to verify.

If you haven’t updated the Edge in a while, I would try that too unless you have custom tunes.

 

I too suspected the CTS3 at one point so I drove with it unplugged for a bit and still had the cut out issue. The 04s have more issues with the CTSs turning off randomly because unlike the 05+ they are not CANBUS. Something about the earlier trucks the CTS doesn't like to play nice with.

 

I wish I had thought about this sooner. Scanned the truck yesterday and pulled the following codes from the PCM: P0381, P0404, P0460, and P0471. In addition, I got these codes from the cluster: B2658, P1139, C1284, and B1352.

Some of these are explainable for other reasons. The P0460 for fuel level sensor circuit fault is probably because I have an S&B 60 gal tank and it stays at full for a couple hundred miles before it starts reading lower than 99%.

The cluster related codes I'm guessing are due to it cutting out when the truck cuts out. Makes me think the problem isn't in the cluster as the cluster is losing input from the PCM. I would love to know the circuit routing on this stuff to know what passes through the cluster and what terminates at the cluster if that makes sense. The EBP code and more than likely the EGR code are probably left over from when I drove with the EBP unplugged.

I cleared the codes and I'll drive the truck for a couple of days till it acts up again and then scan it to see what returns.

 

Update:

After clearing the codes, I've been dailying the truck. It acted up last night while getting on the freeway. Scanned it this morning and the only code to return is the B1352 - Ignition Key In Circuit Fault. Highly unlikely that's anything. I've seen that code on dozens of trucks that have no real issue. I'll dig into it just in case. Stranger things have happened.