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2001 Crank but no start - problem & fix

hightime81

NAXJA Forum User
Good evening all!
my buddies 2000 sport had a crank, but no start issue over the weekend and it presented as the crankshaft position sensor, which i've read is pretty common. odd thing was that all the gauges were working normally rather than being dead. this threw me off some, but we went ahead and verified the fuel pump was working, switched relays around, then pulled the harness and found that the CPS was out of spec (which i figured was the culprit anyways). replaced the CPS and good as gold (other than the fact my buddy left a wrench on top of a pulley which went directly through his radiator when he fired it back up).

basically just wanted to put it out there that the CPS failure can present without the gauges failing.

thanks to NAXJA, b/c i got all of the info i needed for the diagnosis here!

Edited to confirm that it is a 2000, not 2001. (140K, AW4, NP231)
 
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FYI, the "no gauges" "scanner/reader can't connect with PCM" and "NO BUS" issues are related to a shorted to ground crank sensor. The crank sensors have other ways of presenting problems--out of specs, and thermal failure are two other issues.

Congratulations on a job well done.
 
How common is the 'thermal failure' of the CPS, Joe?
Wondering because Wife's '98 ZJ 4.0 (which uses a different CPS) just started running like *poop* as soon as she got home. OBD II code said intermittent signal from cam or crank sensor. Changed out the cam sensor right away, engine still hot, still ran bad. After letting it cool I started it to put up on ramps and it ran fine. Changed out the CPS anyway and keeping my fingers crossed. Interesting tidbit while I was calling around. The OEM ZJ (and WJ, same one) CPS's are on national backorder with 1400 orders waiting. I gave them a part number and they crossed it to the new one. Now the best part: Retail has DOUBLED from $55 to $110 on an unavailable part.
 
Bad news on the price change/back order, going to be a lot of shocked owners.

The thermal failures aren't rare. Usually present as the engine dies, you can crank but it won't restart until it sits and cools down. Some have popped the hood and poured cold water on the crank sensor and VROOM-VROOM, start right up. The thermal failure also occurs with the coils.

You can stress test them with a heat gun.
 
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