I had 12 volts going to the red wire at the IPR plug. I plugged in the IPR, grounded the yellow wire, cranked it and got 2000 lbs pressure. I had a spare PCM and dropped it in but it didn't help. I cleaned 3 grounds: one near the PCM on the left fender apron, and two others to the left and forward of the drivers side battery. What now?

 

Continuity tested wire to the PCM?
(pin to pin)

Bill

 

There is continuity from the IPR pin to the PCM pin
Chuck

 

Do you have a scanner?
Multi meter with HZ?
I would test for HZ ground sig at the IPR connector.

Bill

 

I just have a simple VOM. My scanner (an Actron that I'm returning today) doesn't work on this vehicle. Multimeter with HZ sounds interesting.
I checked the yellow wire while cranking and there's no ground. It should show something even though it's a pulsed signal.

 

Sounds like his IPR solonoid crapped out ...

IIRC .there was 12 V on both pins, while plugged in , w key on ...

Careful ...(Mushroom cloud )

 

Rick

The IPR is only 5 to 20 ohms resistance.
If you test the pins to ground you will get batt voltage
on one pin and the other will be a lower voltage from the coil.
This is without the ground sig applied.

OP
The PCM you tested with was the same DPC?
Chip?

Bill

 

May have been why I needed an IDM after prodding around with a test light ...

Has OP checked the resistance in the coil?...

 

That might have been from ML's

Blue

 

I wish I could blame it on that ,,too early in the day ,

Flash light in mouth ,,test light , key on ,power to ground ..













Poof...

 

oh to have been a fly on that wall!

 

There's 12 volts to the IPR with 10 ohms through the solenoid coil and if I ground it I get full pressure from the HPOP. There's continuity back to the pin on the PCM. The swapped PCM was identical to the old one.
If I can't get this thing figured out soon I'm going to make my own pulse width modulator (DC motor speed control) and run the HPOP manually. sounds crude but would probably work.

 

How would you control the PW as needed (load)?

If you are not getting the signal ground out of the PCM
its possible you are not getting the ground into the PCM.
The PCM has 5 or 6 ground inputs.
What year is your truck?
I will see if i have the ground input pin #'s.

How did this all get started? (changing pump)

Bill

 

He never said if he changed the IPR or not ....

 

It's a '96. I was going to look at Tim's wiring diagrams but the link has been removed. I couldn't see them at home on my laptop but I'm on a different computer today.

Rick, the IPR is working except it's not being triggered by the ground through the PCM.

Knowing exactly what is supposed to be grounded would really help
Chuck