NissanDiesel Forums

At most start ups and shut downs my truck makes a high piched screaching noise. It only lasts a few seconds. I believe it is not starter related but it only happens while the engine is turning over.
The noise seems to come from the front of the engine . The noise is like metal dragging against metal.

Remove the fan belts and try it then. If the noise presists then it might be an internal problem. If it is quiet then check the idler bearing on the belt tensioner, the alternator by simply spinning the pulley, the water pump by the same means and finally turning the pulley on the power steering pump. The idler bearing is my bet but ,,,,,,,,,,,, shrug

Have you found the solution, I'm having the same Problem.

Not yet.

Did you check fan clutch?

The noise is coming from the IPC.
I think the motor gear is spinning on the nylon gear.

If the noise is coming from the IPC motor, it's probably a dry idle bearing. You can disassemble it and lubricate it. Ignore the "Contact Discs" text in the pic below.


Also, there's a lot of info on testing them (and running them manually) in this thread.

I made a short video of testing a couple of them. Link to vid is in this post.

dn29626 wrote:Where is the idle bearing you mention located?

On an armature (any armature, I think), the idle end bearing is the bearing that is not loaded in normal operation.

In the case of the IPC, it's the end that doesn't have the worm drive on it.

But who cares? You're going to grease them both anyway, since it will be all apart . And extra new grease on the Geneva gearset too. And the worm.

If my relay is bad, where do i get a replacement?

I think I bought one from Mouser.com or Digi-Key or Newark. It's not a plug-in part; replacing it requires careful soldering. I often use a larger relay (both in current handling capability and form factor) that won't fit inside the OEM case, and then I mount it outside the case and run extension wires to it. But I think I replaced one relay in a DPC a couple years back with one that does fit inside the case; I can't recall.

dn29626 wrote:With the DCP black box bad, does this disable the starter?

.

No. The crank circuit is entirely independent of the IPC/DPC, except that the DPC will move the IPC to the "Start" position while cranking. The DPC can't interrupt the starter.

It will not start or shut-off with the key.

The no-crank condition is one problem.
The no-shut-off is back to the DPC/IPC problem(s).
I'm guessing you have at least three problems here.

• Starter/switch/wiring;
• IPC noise/wear
• DPC buzzing and possibly not furnishing enough current to the IPC.

The no-crank is straightforward to test: apply power to the little 1/4" or 5/16" spade terminal on the starter and see if it cranks. If so, use the FSM to backtrack up the circuit and figure out what's failed (wire harness to Ign. switch, the Ign. switch itself (it does go bad), or a fusible link or harness connector upstream.

The DPC/IPC problem? I would probably run the FSM IPC test I linked to, to make certain that the IPC is moving to each position correctly. You might even find out that the IPC doesn't make any noise when you run the test, that the noise it makes is due to the failed DPC supplying "noisy" current due to the bad relay.

Lastly, the DPC's relay needs inspection. But I'd leave that for last.

I removed the IPC and powered it up with jumpers. It made the screech noise several times during testing, even with the cover off. Is it OK to use white lithium grease in it?

I suppose i can lubricate and reassemble the IPC and ignore the noise/wear for now and focus on the DPC. I prefer not putting a cable control to the injector pump, but i am considering it to get it running.
Point out to me (or link) the correct alignment of parts in reassembling the IPC.

I jumper wired the starter, nothing. I think the starter has died. I suspect it's failure may have caused the DPC problem.

dn29626 wrote:I removed the IPC and powered it up with jumpers. It made the screech noise several times during testing, even with the cover off.

I would not expect the Geneva gears to make screeching noise, and rarely the worm. I'm sure you're hearing the armature on the bearings it rides on. I don't know how difficult it is to get to the far end of the armature and put some grease in that bushing, but that's probably where it's dry. I show the bare armature above, but I can't recall how it was to reassemble.

Is it OK to use white lithium grease in it?

Yup.

Point out to me (or link) the correct alignment of parts in reassembling the IPC.

The 5th pic in this post of Philip's is the best I have available.

I jumper wired the starter, nothing. I think the starter has died.

Yup