How do you test a CPS?

[falcon556]

You are having problems. You think the crankshaft position sensor or the camshaft position sensor might be bad.
Before replacing, is there a way to test them and avoid wasting money?
I searched with no luck.

 

[langer1]

200 OHMS +/- 75 OHMS

 

[Matthew Currie]

Langer's values are for 87-90 Renix systems only. 91 up CPS should read infinite resistance (open circuit/out of range on a digital meter). I believe the connections on a 91 differ from those on later ones, but the principle is the same. As I recall, this may be one of the few things that the Haynes manual gets right, so that might be a useful reference for pinouts if there is one at hand.

 

[falcon556]

I believe the connections on a 91 differ from those on later ones, but the principle is the same. As I recall, this may be one of the few things that the Haynes manual gets right, so that might be a useful reference for pinouts if there is one at hand.

So, basically you can test for a short and that's about it.
Not very usefull

 

[Matthew Currie]

So, basically you can test for a short and that's about it.
Not very usefull

Yup, that's about it. I don't have any shop manuals at hand, but it might also be possible to test for voltage output with it disconnected and engine cranking, but I'm not sure about that. ON the other hand, with the post-90 system, a totally bad CPS should set a diagnostic code.

 

[falcon556]

Yup, that's about it. I don't have any shop manuals at hand, but it might also be possible to test for voltage output with it disconnected and engine cranking, but I'm not sure about that. ON the other hand, with the post-90 system, a totally bad CPS should set a diagnostic code.

Is there a way to test the camshaft position sensor?
Once, in a different car, I had a code that was pointing at both sensors.
I cleaned the connectors and fixed it but always wondered how I could test it.

 

[SanDiegoXJ]

a totally bad CPS should set a diagnostic code.

Actually...the damn thing just wouldnt start if the CPS took a crap. It would turn and turn and turn, but you'd never get a spark if the CPS was shot.

 

[Matthew Currie]

Actually...the damn thing just wouldnt start if the CPS took a crap. It would turn and turn and turn, but you'd never get a spark if the CPS was shot.

That is correct, but it should also set a code anyway. The engine does not neet to be running to throw a code. The same thing should happen if you have a dead cam position sensor. When this happened on my stepson's 93, it set the code while cranking.

Of course, my luck with OBDI codes has been mixed. Sometimes it seems the engine could fall out on the road and the OBD wouldn't know it.

 

[falcon556]

Actually...the damn thing just wouldnt start if the CPS took a crap. It would turn and turn and turn, but you'd never get a spark if the CPS was shot.

It was missing a lot and it was faulting both sensors.
Cleaning the connectors fixed it.