Chrysler Repair: 00 Neon: power supply to pcm/how to test crank sensor, pulley bolt, afew minutes

Question
QUESTION: in the 2000 neon, is there a fuse for the computer? and for the crank sensor. how would you no its going down?

ANSWER: Hi Jordan,
Fuse 21 in the box under the hood provides power to the pcm all the time, fuse 10 in the cabin fuse box powers pcm in start and run. The crank sensor will often cut out and then after afew minutes the engine will start and run again...only to go through the same symptom. It is caused as it warms up it fails...cools and recovers, etc. You can check in the failed condition where you will find that the pulsing that should be seen across the gray/black  and black light blue wires is mission. But you have to do this by turning the crankshaft by hand using a wrench on the pulley bolt. With the ignition switch in the run position the voltage should pulse between 5v and 0.3v several times per crank revolution of the cps is good. If no pulsing, then it is bad.
Roland
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---------- FOLLOW-UP ----------

QUESTION: hey roland, i couldnt find fuse number 21. under the hood relay box did not have a number 21. the cabi fusebox only had up to number 20.

where would number 21 be? and also i do not no if i mentioned this but when the no bus appears, the cluster pannel shuts off completely.

Answer
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Hi Jordan,
I have the '97 and the '01 manuals and both circuits show a fuse #21 to provide full-time power to the pdc. In the 97, there are 13 fuses and #21 in in the rear of the box by the horn relay, in the '01 there are 16 fuses and #21 is next to the most-outboard fuse in the 2nd row of fuses. The fuse is 20 amp. it is for circuit A14.
About the other fuse that powers the pcm, in the cabin, it is #10 (not 21!) so you should be able to find it. It is 15 amp and is for circuit F12.
I have told you that 'no bus' is saying that the bus wire from the body computer to the cluster is 'open' and so it is reasonable that the panel shuts off in terms of any readings on the meters, etc. I think I earlier suggested that you check the circuit board plug at the cluster about this issue.
Roland