TPS voltage too high??

Checking my TPS, found the voltage from the harnes was at 12 volts. Specs say 5 volts, now what? Adjust TPS to that value?

thanks
Wade
88 4x4 auto, 4.0L with 214k and still going

My first guess is you have somthing major wrong. This is time for professional help.

I moved to a new town and called the local jeep dealer. I talked to the service dept and asked if they had a guy familiar with the Renix ignition system and was working there when my 88 XJ was new.

They put the mechanic on the phone and talked to him, he passed the phone interview. My recommendation is to find that mechanic who lives close to you and take in your XJ.

There is a test set which the dealer should have, ask about that also when you make the call, for the Renix system. They should be able to figure out the problem/fault with your XJ. Should only cost you 1 hour of labor for the diagnostic.

I get 4.6 volts as the source voltage for my TPS when I intalled my new TPS a couple of years ago.

How does your XJ run otherwise?

Whoops! -- that 5vDC source is regulated at the ECU or the TCU (depending on which plug you're measuring) -- sounds like there may be real issues (I'd start with the typical suspects and disconnect the battery while you inspect grounds and the ECU and TCU connectors) ...

... What plug are you looking at (the flat one or the square one?)?

Just for "reference", measure the FLAT one - pin A to ground (that's the ECU's 5v output)

If you've measured a pin on the Square one at 12 Volts - and are sure sure sure that you're 12V is dead-on there may be some issues in your TCU - I've seen em loose a ground cause of a bad windshield gromet (the TCU gets its connector wet and a little corrosion isn't a good thing). Again - with the battery disconnected - disconnect the TCU's harness and look for corrosion on the pins and sockets... You ay be shopping for a TCU in the not so distant future, so looking for any identifying makrs/calibration labels on the TCU could be a good thing... as long as you're in there...

tranny not downshifting

Well it helps if you have a properly calibrated meter!! DUH!!! Ok its not 12v, it is 5volts and the voltage to the throttle is .71, Chiltons says it should be .8, is this close enough?
Could this cause my tranny not to downshift when stopping?
What else could cause this?
thanks
Wade
88 4x4 MJ 4.0L auto

On the auto the output voltage should be about 82% of the input. So in your case about 3.72. The input for a manual tranny is about .8volts. Here is a link to the adjustment procedure. A bad tsp or adjustment often causes auto tranny shifting problems. Good Luck. Greg

http://members.tripod.com/BillyXJ/SENSORS1/page1.html