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Crankshaft Position Sensor

k.smith904

NAXJA Forum User
Location
Jacksonville, FL
So I brought my 87 renix into the local dealership the other day after i couldn't figure out whats wrong with it and they told me what I pretty much already knew. They said it was one of 3 things:

1. Crankshaft Position Sensor
2. Throttle Position Sensor
3. Ignition Coil

Heres my question: How hard is it to install these by myself, i'm not an idiot, but certainly not a gearhead either.

They quoted me at $170 parts and labor for the CPS and install. Too high?

How much would each part run me if I were to order them myself? (Ballpark)
 
In order of easiness (IMO)

3...2....1.

Just did a CPS on a 88 last weekend....sensor cost $35 at Advance Auto and took an hour or so to install (never having done one and it's in a tight spot).

TPS is really easy to get to.....I don't recall the price of the one for my 99 off the top of my head...for some reason $60-70 rings a bell...but don't quote me on that.

Ignition Coil (we tried first on the 88 last weekend) was about $55 from Advance and super easy to install.

What are the symptoms of you problem?
 
no start, it will randomly start up, then I drive it around the block, park it, and when I try to crank it up 10 min later it won't start. I've cleaned the grounds and all the sensors as good as i could.
 
Quick fix just unplug then replug in the CPS... Maybe blow it out with some canned air. The connectors on those are the known cause for going bad. I had to do it on my wifes rig about 2 months ago cause it wouldn't start and has started fine everyday since then.
 
The renix will start with the TPS unplugged, and definately try unplugging the CPS and cleaning the connector as XJ Stryker suggested. Did the mechanic even bother troubleshooting your problem, or is this a cash register diagnosis? I can't stand it when "professionals" start guessing and throwing parts.
 
CPS is the way to go starting from the begining. The wiring goes bad on 87-90 Renix XJ's. Google Jeep Reference J007 it is definately a needed service procedure for Renix XJ's. An easier but more time consuming way to replace the CPS is to support the trans & transfer case with a floor jack & a block of wood @ the pan. Then remove the crossmember + front driveshaft. Lower assembly and use 7/16" or 11mm socket with extensions to remove the CPS. Unplug and remove. You can do it by routing your had all the up the bellhousing with the transmission bolted up but it's a bitch. Good luck with your XJ.
 
k.smith904 said:
They quoted me at $170 parts and labor for the CPS and install. Too high?
How much would each part run me if I were to order them myself? (Ballpark)

Are they just changing the CPS only, or are they doing the Technical Service Bulletin to replace the CPS and wire it directly to the ECU?

The TSB is for 87 and 88 only. To tell if the TSB has been done already, the connecter for the CPS will be plugged into a small wire harness that goes to the firewall right underneath where the main harness passes through. If it has not been done, the CPS will still be plugged into the fuel injection wiring harness.

More info:

TSB 18-51-88

Parts:

83100066 kit for automatic trans, has new CPS, harness, and dust cover.

83100063 kit for manual trans, has new CPS and harness.

Instructions are not included with the part, must print out the TSB.


My copy is old so part numbers may have changed, and hopefully still available if you need them!
 
also, the tps on 87-90 needs to be adjusted with a voltmeter/mutlimeter to factory specs. its not plug and play like the 91-and up, unless you get lucky on the install.
 
well im getting the heep towed back home today so I'm gonna try to mess around with the CPS and try to clean it and the TPS the best I can. Then if that doesn't work I'll start throwing parts at it.

Is there anything else that is common in the renix xj that would cause a random no-start?

Heres what I'm going to replace so far:
CPS
TPS
Ignition Coil
Spark Plugs

anything else I should grab, or try?
 
I would bank on it being the CPS. Thats a quick fix. all you need is an 11mm (or 7/16") socket (swivel would be good) a long extension and a ratchet.

two bolts off, swap it, and two bolt back on. done.
 
well I got it towed home so its safely in the garage, I cleaned out the TPS, CPS, MAP, and all that good stuff; but my battery is completely dead so I'm gonna have to wait till my dad gets home from the night shift in the morning to test it out, wish me luck...
 
what ever happened... Im having the same problem... 90 XJ...



Ken
 
HAVE YOU checked the cps? obviously tons of others have, and for a lot of them it was the cps.
so if you read this thread and didnt check your cps.... you'd be missing the entire point of searching!
 
I'd recommend doing the cps bracket alteration. (basically cutting the screw mount holes so they're open semi circles. This way you can just back off the mounting screwand slide the new one on. After dropping a screw into my bellhousing, I learned the hard way. It'll easily make changing the NEXT cps a half hour procedure tops.
 
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