Crank position sensor ohms-have searched

[crazy4moab]

Does anyone out there know what the ohms should be for the CPS? I can't seem to find it in my service manual. Also another question, I've been having issues with my ignition the past year. I've gone through 2 ignition modules and 2 CPS's. Is there another component that may be contributing to this type of problem??? If so, WHAT THE HECK IS IT!!!!! Can you tell I'm going crazy because of this! :helpme: Any info that you can give would be greatly appriciated

[Matthew Currie]

on an 87-90 the CPS should read 125-175 ohms on a warm engine.

[SimpleXJ]

PROCEDURE


Near the rear of intake manifold, disconnect sensor pigtail harness connector from main wiring harness.
Place an ohmmeter across terminals B and C (SEE Image). Ohmmeter should be set to 1K-to-1OK scale for this test. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

http://home.earthlink.net/~jaggedsteel/cpscon.gif


SimpleXJ

[Eagle]

on an 87-90 the CPS should read 125-175 ohms on a warm engine.

Just to play devil's advocate ... how do you take a measurement on a warm engine if the engine won't start?
:wierd:

[lunghd]

Resistance should be close to 275 ohms, IIRC.

You can also check it by measuring AC voltage it generates when cranking motor. 0-5 VAC scale on DVM - should show .5 - .8 volts AC. (It's a magnet & the flywheel spinning by it turns it into a tiny 'generator' - that's how it tells the engine computer when the engine is at TDC.)

More detailed diagnostics at : Basic Diagnostics (http://home.earthlink.net/~jeepcherokee/Engine/Basic%20Diagnostics.htm)

[Matthew Currie]

Just to play devil's advocate ... how do you take a measurement on a warm engine if the engine won't start?
:wierd:

Torch? :flame:

[Matthew Currie]

PROCEDURE


Near the rear of intake manifold, disconnect sensor pigtail harness connector from main wiring harness.
Place an ohmmeter across terminals B and C (SEE Image). Ohmmeter should be set to 1K-to-1OK scale for this test. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

http://home.earthlink.net/~jaggedsteel/cpscon.gif


SimpleXJ

This only applies to Chrysler systems (91 up). The REnix system should definitely deliver an ohmmeter reading, and infinite resistance is a positive diagnosis that it's dead

[SimpleXJ]

Matthew, you're right, this diagram and procedure is out of my 1996 issue FSM. I shoulda asked what year his was.

SimpleXJ

[crazy4moab]

Thanks for the input, guys. Sorry about not stating the year but my sig. was there. Anyway, its a '90 4.0L. They are a glorified ABS sensor and work on the same principal. I found out that the problem was the ingnition module. Went to Autozone and had it tested. (easier part to remove) So now that brings into effect the second question that I asked. Is there another component that is causing my module to fail. This new one makes 3 in the last year. HELP!!!!!!!!!!!!!!

Thanks for the pic "simple". But I was looking at and was scratching my head cause mine looked nothing like that. Sorry, again, for not stating the year.

Thanks again folks!!!!

[rws]

Recently checked CPS on my 90 4 liter. Resistance was 232 ohms on a cold motor, output voltage was .42 volts cranking. This vehicle starts and runs perfect.

[Runnin'OnEmpty]

Crazy4, what type of sparkplug wires are you running? These Renix systems do not take well to the very low resistance types; you need at least about 3-4K ohms per foot. Solid cores will not work at all.

[rws]

Check your wires. If they are to high a resistance in your plug wires you will have arcing in the coil which will destroy it internally.