XJUSMC

99 4.0 4x4 no cruise control

I'm having an issue with a rough idle condition and code p0122 low voltage to the tps with no check engine light. After checking the tps with a multimeter it came back fine. My horn does not work so after going through the fuses, grounds, and alot of searching on several sites im going to replace my clockspring. (it's in the mail)

My question --- Does he airbag light come on when you start the jeep, similar to the check engine light doing its self/bulb test. Mine is not coming on, and I am not having the chime issue.

Just tring to further track down issues. Please share any other thoughts. Thank you.

salad

Clockspring

TPS ground goes through there

CCKen

Yes. The Airbag light should come on for about seven seconds then go off during the bulb check (before starting) and when the engine is started without doing the bulb check. If the light doesn't come on the bulb may be burned out.

When you did the TPS test, did you check the voltage coming to the TPS at the TPS harness connector? With the ignition switch to RUN, you should see 5 +/- .5 volts at the connector pin cavity with the Orange wire.

Ye Ol' Cherokee

YES!

CCKen

No!

XJUSMC

When you did the TPS test, did you check the voltage coming to the TPS at the TPS harness connector? With the ignition switch to RUN, you should see 5 +/- .5 volts at the connector pin cavity with the Orange wire.[/QUOTE]


Yes I checked all conections at the harnes. It was dead on at 5 V.

and thank you for answering my question.

Ye Ol' Cherokee

Maybe So!




I had the identically same issue, and that was my fix. Maybe i just got lucky lol

CCKen

To isolate the clockspring as the potential problem remove the horn relay from the Junction Block and see if the cruise control returns and the rough runnng goes away. Obviously the horn still won't work.

If you don't have an Airbag light because of a burned out bulb you won't see the Airbag light go away, or know if it was on steady to begin with.

The only evidence you'll have is the Cruise control returns.

A defective clockspring is usually responsible for allowing horn relay control coil voltage to leak to the cruise control system, then to the PCM 5 volt supply, which normally causes a TPS high voltage DTC.

You have an odd duck on your hands mate.

A strange thing about P0122 is that a defective TCM can cause this. Disconnecting the TCM may make the P0122 go away(?). Just a bit of FYI.