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Help: GM 3800 engine ignition experts

Gentlemen,

REF: previous posts/threads were under the subject: "Help: where to buy GM style electrical connectors"

the car: 1994 Olds 88 Royale, 3800 engine, L27

Two scan codes are persistant/current:

  1. P0321 - 18X Interrupts Lost
  2. P0341 - Intermittent Cam Signal

I did the pertinent continuity/ohm tests on the wiring to cam and crank sensors, ICM, 8 way jumper harness, and PCM.

I tried a new crank position sensor: same codes. The cam position sensor was recently replaced by the owner.

I just performed the diagnostic procedure on the Spark Reference Circuit. The Spark Reference voltage at the PCM backplane, pin RB6, is 2.92V with engine running. GM Spec calls for 2.5V.

In a similar test, Fuel Control, pin RB8, is 2.45V. Spec calls for 2.5V. Seems ok here.

What do you think? Is the SWS/amp or Buffer/Amp in the ICM bad, requiring replacement of the ICM?

TIA Bill

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Bill
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Bill,

You got a P0341 for an intermittent Cam signal. Why did you change the crank sensor? There was no reason for this.

I bet that if you changed the cam sensor, your problems would go away. If they don't, you might have a wiring or connector problem for the cam sensor.

Just because the cam sensor was previously replaced before, doesn't mean it's good. The pins on the connector could be broken, too. I have seen the female portion of the connector break off (meaning the little spring portion.).

Just a bit of input, GMdude

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GMdude

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Bobo

Crap, I was staring directly at the problem for over an hour. The RB9 female pin in the PCM connector was sloppy.

Many thanks to Bobo and the others that provided help al>Gentlemen,

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Reply to
Bill

Bobo,

Um,... he did what he needed to do??? He found a sloppy connector pin at the PCM. It was one of my suggestions, that he check the connectors and wiring.

GMdude

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GMdude

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Bobo

Bobo and GMdude,

I missed some of your past posts because they did not line up under the original threads. I just now found them.

Yes, you told me to check the PCM connections. However, it was my bad because when I backprobed the PCM, I in fact caused the RB9 pin to make contact with the male PCM pin. Thats why I initially deduced that the square pulse wave was being delivered the the PCM. Later during a road test, I hit a bump and the MIL came back. Thats when I was convinced that it had to be a bad wire.

Yes, the cam signal does go to the ICM, but then comes back out, through the 8 way jumper harness, then on to the PCM.

Thanks for the help. Bill

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Reply to
Bill

Bobo,

If he had found nothing wrong, my next suggestion would have been to check pins at the PCM. I have been there, and done that many times.

By the way,... Chief, it's not a 321, if you were talking about displacement? It has a displacement of 231 cu. in. The old 231's have long since disappeared, odd and even fire. This 3800 bares very little resemblance to those junk dinosaurs, physically, and in reliability.

GMdude

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GMdude

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Bobo

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