When testing the cps when you crank the motor should the reading jump around.when cranking mine jumps from .45 to .55 or should this be one solid number? 89 xj and of course it wont start.I have done the 1 through 5 thing from cruiser post and it did help all the interior lights got brighter and it started.thought I had accomplished something,but to no avail.the next morning no start so I go through everything again cleaning and spraying it all again jiggling wires and it starts yea.so it runs I drive it around park it come out the next morning to check ,no start.this thing is wearing me out any thoughts.

 

I can't answer your CPS question, I've never owned an XJ of that vintage. I'm sure someone else will know.
It would be good to know which wires need to be jiggled to get the engine to start.

 

Yes, the voltage varies. Yours is a bit low but I've seen worse.

Wiggle the wires while cranking it over and observing the meter reading.

Check for proper CPS wire routing.

 

Just to be doubly clear, "no start" means it cranks but doesn't start?

 

yes it cranks good. when it does run it seems to run fine i can drive it no problems.but then ill come out the next day and it just cranks.i really dont know if the shaking of the wires really did anything or not.i would move something try to start,move something try to start.then once i moved those transmission plugs it started once.and when i did the grounds and wires it started once.so i dont know?i metered the coil,had the icm tested,it passed.not sure where to go from here

 

what really sucks is i just got it about a month ago,test drove it dove it home wheeled it through some light mud trail after a rain.no problems then one day BAM no more.

 

Of my Tips, which have you completed?

 

1-5,7,910,

 

Have you tested the CPS during the no-start condition?

 

yes and those were the readings i spoke of earlier.there is a video on youtube where a guy is working on a 96 cherokee with a no start issue.he checks the 5 volt reference from the computer on the tps,and pulls all the sensors on that circuit to find the sensor thats not working.but i cant find a decent wiring diagram for a 89.the one in the haynes book dosent even show a cps sensor in it for that year.and i dont now if the newer diagram would be right

 

What I'm getting at is the voltage on the cps is 3.5 not 5 coming from the computer so is this right because it is on a different circuit then the tps and therefor a lower voltage is required for that circuit. Or one of the sensors on the circuit with the cps is bad and if so what sensors are on that circuit.

 

Totally different system he's working on. Fugetabout dat one.

 

CPS generates it's own AC voltage signal TO the ECU. It receives nothing FROM the ECU or anywhere else. Shares NOTHING with other sensors.

 

Did you check for spark while it was not starting? Possibly a fuel issue?

 

Well it's fixed turns out it was the icm hitting it with a hammer while cranking it seems to be a good test, it started up.so replaced icm and she starts fine.