I really need some input from you guys! I am helping someone with a 97 PSD, which runs sometimes, and other times it just cranks but won't start. The codes that come up when it won't start are P0344 (Camshaft Position Sensor A Circuit Intermittent (Bank 1 or Single Sensor) and P0603 (Internal Control Module KAM error). It has had three new CPS's, so it's not that.

I pulled apart the harness from the CPS, to where it feeds into the main harness and found no shorts, or damage. Where else do they tend to chafe? I am assuming it is arcing/shorted somewhere, as those are the only codes. When I watch with AE, ICP only reaches 280-300 PSI while cranking when it won't start. But Duty cycle isn't increasing, so I don't think it is leaking HP oil, or a faulty IPR. I own IDS as well, but didn't have my VCM with me. Oh, and no HP oil related codes either.

Please, anybody have any advice? This gremlin is a real SOB!!!

I also forgot to add, while cranking the tach does move.

 

With ICP at 280 ,the IPR duty cycle should increase .

Unplug the ICP sensor & try starting it , look for oil leaking from the sensor. IF PCM sees low ICP at startup, it will increase DC% to 50-60% full closed .

THe CPS code is from extended cranking with a no start...

 

So the CPS wiring shouldn't be the issue then correct? I figured that wasn't the problem after checking wires, especially since the tach is moving while cranking. But shouldn't ICP codes set? When the truck dies and won't restart, ICP will not go above 280-300 PSI, and Duty cycle remains in the green. But I didn't know if that meant there was no CPS signal. I'm not sure why DC isn't increasing.

I did notice the IPR solenoid body is really loose on the IPR, but I didn't think that was a big problem.

 

The PCM is not seeing the ICP ....

 

So if unplugging the ICP sensor makes it start, then it's the ICP sensor correct?

 

Any additional advice? I will be helping with the truck again tomorrow, and want to come with all possible info so we can get it fixed. Thanks!

 

Tighten the tin nut on the ipr, just don't overtighten it.

 

.....Ooooo, bet this is the intermittant problem here!( IPR Sol. Body loose)

 

Not always . Some times the IPR is stuck open as well. In your case it appears the PCM is not telling the IPR to close. Could still be a few things ,including PCM .
THe connection on the ICP could also be loose. With the key on you can test the wiring to the IPR .Use the connector on the side of the fuel bowl ,its easier to get to.


With a meter you can test the ICP :ICP should be:

key on:.25-.4V
low idle:.75v-1.0V
normal operating range:.65-3.6v
During cranking ,watch for what would be idle voltage to increase. if it does then the PCM is most likely working ..


, If you hold the ICP connector looking into it with the latch on top, the left pin is Vref, center is ICP signal, and right is Signal return. The corresponding wire colors should be brown/white, dark blue/light green, and grey/red.

 

The factory '97 hard/no start diagnostic sheet infers the injectors won't fire unless you have at least 500 psi at the ICP. Also says the CPS signal must exist before the IPR is commanded over 14%.

I'd encourage you to listen to Rick, he's made a few posts on this topic in my short tenure and I haven't seen him steer anybody wrong yet.

 

Ok I got a chance to play around with the truck quite a bit today, and I am pretty sure I have it figured out. I got it started, and drove it around until it warmed up, which is when it died on me driving down the road. I cranked it over, and monitored ICP, duty cycle, RPM, and system voltage. I think it is the IPR valve.

I finally got it to throw a low ICP code. However, P0344 and P0340 still showed up when reading DTC's. But I don't think it is the CPS/wiring, because I am getting an RPM signal while cranking. Duty cycle climbed to 50% but ICP was only getting to 300 or so. Unplugging the ICP did not make it start. So next I will be replacing the IPR valve, and hopefully that fixes it. Any other input? Does the IPR valve sound like the problem? Thanks everyone!

 

I recently had to acquire a new IPR bail-connector, due to Diesel soaking and removal and re-install during my PCM related "no-Start"...I could start the engine and wiggle the harness and kill or miss the engine. Also it would get progressively worse when the engine heated up....or just kill the engine with no codes or CEL....as I ran down the road.