Help with Crank Position Sensor - 89 Jeep Cherokee LTD

The plug is usually the issue. I use a good clean with contact cleaner and then use dielectric grease on the plug seal skirts to keep it good.

You can just cut out the plug and solder and heat shrink the connection. The newer double walled automotive heat shrink comes with glue inside to waterproof it.

And even with a new one, my 88 doesn't start any faster. It still seems like it cranks a long time but starts every time. It is the nature of the beast. I find a clean on the TPS plug and socket seemed to speed up starting, well maybe....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

NT wrote:

Hi Mike:

Thanks for your note.

Maybe you can help clarify.....

On some posts, there has been reference to the connector being above the brake booster - on my 89 - I don't have any connectors in that area. I can't see where the CPS wires are routed, although I can see the sensor with the harness heading off to the passenger side of the bell housing - then I loose it. How do I locate the connector in question?

Thanks for your help.

NT did pass the time by typing:

Lots of cranking usually indicated a no/low fuel pressure problem in fuel injected vepickles.

Yea.. The number is printed on the CPS tang right next to the bolt that holds it in.. way up where you of course can't see it. :/ There might be a paper tag somewhere on the harness.

There are kits to move the CPS up front to the harmonic balancer, but no bypass kits that I'm aware of.

Dunno if this helps, but for the ZJ.

On my neighbor's '96 XJ we found the CPS to be on the driver's side and the connector was connected on a bracket held on by a bolt on the rear of the intake manifold

They put it in a sweet spot.... right on top of the back of the exhaust manifold behind the TB where it gets nice and warm....

It is a 3 pronged plug with two wires in it. Red and white I believe.

Mike

NT wrote:

I used to have an `89 Cherokee with the 4.0L engine. The CPS connector was on the driver's side, hard up against the firewall, just above the intake manifold.

My brother-the-mechanic once told me that the manufacturer was aware that there were problems with the 4.0L CPS and had issued a repair kit, that didn't really do any good.

You might find this interesting:

It seems that some CPS units were made to stand too far from the flywheel, giving a weak or faulty signal, causing hard starting or no starts. This, of course, doesn't explain why unplugging and replugging the CPS connector can cure a "no start" condition.

NT wrote:

Hi Guys:

Thanks for the tips. I was able to locate the connector (I think). On my

89, the connector is one of the 'water tight' variety. I opened it up and took a look - the inside looked brand new - clean as a whistle - I guess all that sealing really does work - on this connector anyway.

Thanks again.

I just took a few pix of the CPS Sensor and Connector on the driver's side of Ed's '96 XJ.

Send me an e-mail to the address below (remove the SPAM) and I'll send them to you

I sent some pix of the driver's side CPS & Connector to Bill if he wanted to post the pix to his website's tech section.

You can remove it from underneath using your 1/4" socket set with a 7/16" socket on a long extension.

The connector mount takes, I seem to recall, a 10 mm wrench

Thanks Bill!

Clean it anyway - the corrosion you get there is too thin to really see anyway. You probably cleaned it enough just with the friction of unpluging it.

I use the waterproof dielctric grease on that rubber seal on the plug

- seems to make the cleaning last longer. Works especially well on the TPS and IAC connectors on the throttle body.

I will second that. The connection is only for low power computer signals and the amount of corrosion that causes them to crap out isn't visible with the naked eye. Think how many times a hard drive buss cable fails while still looking good... Contact cleaner works on them too.

I just had to do my TPS connection yesterday because it was revving really high on start up. It wasn't visibly dirty, but a fast clean and she is starting and idling great again.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Thanks guys:

I was able to take a look at the pix. My sensor definitely looks different - that is, the part that you can see from under the hood - it's more 'boxy - trapazoid' shaped - if that makes any sense. Not sure the shape is any indication of the vintage (ie: whether it's one of the older original faulty variety)?

Thanks for the tips guys:

What are you cleaning with? Some sort of electrical contact cleaner? I can't see how I'd get inside the connector to do any sort of a proper cleaning job (other than a spray cleaner).

Spray contact cleaner and dielectric grease

Thanks Billy:

I have both and will give it a once over.

I put the new one in. Made absolutely no difference in starting, it still has to crank one revolution until the spot in the flywheel passes the sucker.....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

NT wrote: