Might be easier as you suggest to pull the pump. I looked at you tube, nothing. The pump itself dosen't look too meanacing.

I've been driving about listening to the CPS squarewave. Never seems to miss a beat, but the issue of it being inverted has never been resolved. Haynes one way. A major helpline, the other.

Talking of injectors. I pulled the 10A fuse and by chance selected a perfect filament bulb to take its place. 7W. The cold resistance of that works the injectors a treat.

IGN on, Bulb lights bright as all injectors are given a blast. when the normal sequence starts, I got an even 5v waveform across the bulb, with it flickering as one might expect. The evenness of the waves told me there was no major electrical fault with the entire circuit, but of course didn't confirm they were passing fuel. Quite a nifty little test. Yes, I know, it's probably been done a million times.

I ordered a 'new' PCM from an e-bay site. They check them and flash one's details on. They also give a briefing on how to reset it when it's installed.

A fraction of the price of an Autozone unit, and you get to keep the old one for breakdowns. We'll see how that goes.

Any problems and the PS pump will be out within the hour.

Any progress?

Not really. Van is drivable, so not so much pressure to fix it.

The PCM arrived, and I trained it to the car. Took 30 mins. Ran okay, apart from the slight misfire.

Within a day or so, the Cam warning came on again. Back to square one.


I built a simple filter to smooth rather spiky supply to the CPS and it seemed to go longer before a fault. But the fault did come back.

I guess the next thing is the sensor itself. It's just the garage is so hot right now, and I have things I should be doing.

Don't want to let it beat me, but it's not fun anymore.:rolleyes:

That I understand. What I don't "get" is reading a square wave that is "negative" (your description) negative being my subjective based on a negative wave. I'd think there is no physical way to misconnect the connector to the cps, but interesting.
I have a 1996 Lumina that about got me to the point of "not haviing fun" with running, SEL Light. After time, it runs great! Took alot of intense work, something the dealer would not even handle.
Sticking with my 1970 deta 88, times were so much easier then.

Yes, the square wave is a mystery. I sent this off to one useful site just now.

http://easyautodiagnostics.com/ignit...ule_test_2.php




I didn't get a reply last time, but hey, it's a great site to get this far.