Transmission questions

Ok so I know there's alot of questions/post about trans problems. But my issue seems that no has encountered it yet.

Long story short bought a 98 that needed a trans no reverse. Got a trans from a buddy out of an 01. Same trans same plug styles but the main trans harness was cut when it was pulled from his parts xj. Pulling the bad trans out of the 98 was just a nightmare someone was in there things wherent tight and stuff was broken. The main thing that I was concerned about was the black plug that gose in the side of the trans for the solenoids was broken and just sitting there. Didnt want want any problems, so I put the word out for a trans harness and someone answered. Said I could have the harness for nothing but I had to pull it out of the jeep not a big deal so I did. (FYI the trans harness is from an 99 or 01

Got everything back together up and running drives good nice and smooth shift are a little late but I figure it was from the tps code that was originally stored in the history from when I bought the jeep. Ran over to the parts store picked up a new, at this point everything is perfect and thinking to my self man this is the easiest 500.00 bucs I ever spent haha. Well on my way to work this morning the jeep dies at a light.

Bring my scanner home thinking ok maybe the crank sensor took a shit since it didn't want to restart after it died. Go into engine codes with my soulus and find a trans fault code( oh boy great). Go into the tcm and pull up codes and long behold a tps is in there. P0123. Go into data now to see if tps voltage is right. This is what I have.
Idle: .6 to 1.0v is normal
Actual 0.0v at idle
WOT: 3.5 to 4.0v normal
Actual: 11.0v

Yes I did a wiggle test while watching the scanner to see if anything jumps did not notice anything. My question is, is the 99-01 trans harness compliant with the 98? I figured it would be since they are pretty much identical drive train wise.

Hope I filled in enough info for you guys thanks



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According to this thread, http://www.naxja.org/forum/showthread.php?t=1053970, 98-01 should interchange.

1) Did you buy a genuine Jeep TPS ?

2) Have you disconnected the horn relay and re-tested the TPS voltages ?



1) Explained -> Most auto parts stores sell cheap crappy Chinese parts, some that come with a "Lifetime Warranty". These parts are poorly manufactured and/or made from inferior materials. They are often out of specification, or even failed, right out of the box. The ones that aren’t faulty many times will have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep sensors. Numerous threads detail long and frustrating searches for a "problem" that ended up being cured simply with genuine Jeep repair parts.

Cheap parts are cheap for a reason




2) Explained -> COMPLAINT: TPS CODE P0123 WILL NOT CLEAR

A late model Jeep with a 2.5 or 4.0 liter engine and the AW4 transmission comes in with the “MIL” Check Engine Light illuminated and a complaint of late shifts. A scan reveals a code P0123, “TPS Voltage High”, is stored. The scan tools data list indicates that the TPS signal wire voltage is at 5.0 volts at closed throttle, and then ranges up to 11.5 volts. A back probe of the TPS signal wire (usually is an Orange/Dk Blue wire), shows 5.7 volts at closed throttle, with a similar rise in voltage as the throttle is opened. A check of the TPS 5 volt supply and ground circuit prove that both of these circuits are good.
I got a CEL code P0123/122/and 121, Installed a new TPS sensor and it didn’t help. On the highway and noticed my cruise control didn’t work either, and the Jeep was sputtering/stalling, I could smell gas and my left blinker was acting funny sometimes it would turn on, sometimes not...sometimes it would blink 10 times a second like I had a bulb go out, Turns out it was the clock spring.

A check of the TPS signal wire with the TPS disconnected shows the same 5.7 volts. Inspection of the wiring between the TPS and the PCM and TCM shows no faults. A replacement TPS does not cure the problem, neither does replacement of the PCM or TCM.

CAUSE:

The Switch Sense circuit in the Clock spring in the steering wheel hub has shorted to battery voltage from the horn button circuit. When the Switch Sense Circuit shorts to the 12 volt HORN circuit the TPS signal voltage is driven high and remains there as shown. This is because the 5 volt reference voltage used by the Cruise Control “Switch Sense” circuit and the TPS are shared inside the PCM.

TESTING:

Unplugging a faulty Clock Spring should return the TPS voltage to its’ normal readings. Or, you can remove the Horn fuse in your fuse block - this will remove the 12 VDC supply to the clock spring. Once the short circuit is temporarily disconnected, you should be able to reset the trouble code, and confirm you diagnosis of a faulty clock spring.

CORRECTION:

Replace the Clock spring assembly. Once the Clock spring has been replaced be sure to check the sensor 5volt reference voltage at the PCM to insure that circuit has not been damaged by the short to power. Also check the TPS signal range to insure the TPS has not been damaged.

What should tps voltage and throttle percentage be when watching data in trans on scanner? Same as what the engine is reading correct?

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You can test the TPS voltages by following the steps below. Use a Safety pin (or equivalent) as a back probe.


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