99 Issue p0123

[Mudderoy]

My daughter has reported that while driving down the road, constant speed, the rpm drops to about 1k rpm the throttle doesn't work (or do anything) then after a second it starts going again.

The code is P0123. Throttle Position Sensor has been replaced.

[prerunner1982]

Check the connector? Maybe just has a poor contact in there? Wouldn't hurt to test the operation of the TPS anyways.

[4.3LXJ]

Standard or auto tranny?

[Mudderoy]

Standard or auto tranny?

Auto

1999 Jeep Cherokee Sport
4.0L
Auto
4x4
147k miles

[JTHarrison86]

That's tricky right there. Have you tried driving it yourself?

[bluedragon436]

I'd say check the connector, if noting else clean it up some and apply some Dielectric grease.. Could still be a bad TPS, even though you just replaced it..

[Mudderoy]

That's tricky right there. Have you tried driving it yourself?

I have not. Currently it's very rare that it happens. Twice in two weeks.

[4.3LXJ]

Auto

1999 Jeep Cherokee Sport
4.0L
Auto
4x4
147k miles

The next question is if it is in 4th and lock up. If so, I would check the tach. If not, does it loose speed too. If it does, I would check the fuel pump

[Mudderoy]

The next question is if it is in 4th and lock up. If so, I would check the tach. If not, does it loose speed too. If it does, I would check the fuel pump

I'll double check but I believe it looses speed briefly while the gas petal doesn't work.

[jonb8]

Wow I've never heard that one before...Sounds interesting though...Is it a distributor or coil pack Jeep?

[Mudderoy]

Wow I've never heard that one before...Sounds interesting though...Is it a distributor or coil pack Jeep?

distributor

[bluedragon436]

I'd say check the connector, if noting else clean it up some and apply some Dielectric grease.. Could still be a bad TPS, even though you just replaced it..

Sorry... meant to mention the only reason I said could be even if you just replaced it, was because sounds similar to what my 97 was doing, and I replaced the TPS, and it seemed to fix the issue... then started doing it again... and usually if I catch it quick enough, I'll let up on the throttle and give it gas again and usually it works just fine... which is how I originally troubleshot it down to a TPS issue on mine... and started doing it again on mine after replacing the TPS... so replaced it again with one from a different auto parts store... and seems to have fixed the issue.. in my case anyways..

[Mudderoy]

Sorry... meant to mention the only reason I said could be even if you just replaced it, was because sounds similar to what my 97 was doing, and I replaced the TPS, and it seemed to fix the issue... then started doing it again... and usually if I catch it quick enough, I'll let up on the throttle and give it gas again and usually it works just fine... which is how I originally troubleshot it down to a TPS issue on mine... and started doing it again on mine after replacing the TPS... so replaced it again with one from a different auto parts store... and seems to have fixed the issue.. in my case anyways..

Any part can be bad, including this one from the Chrysler dealership.

[Mudderoy]

Hmmm I wonder if it just needs a tune up...

https://youtu.be/DVftEwcgBIQ

[Mudderoy]

Well check this out...

https://youtu.be/C6pDhW1287M

[OldFaurt]

My daughter has reported that while driving down the road, constant speed, the rpm drops to about 1k rpm the throttle doesn't work (or do anything) then after a second it starts going again.

The code is P0123. Throttle Position Sensor has been replaced.


It sounds like a short in the Sensor +5 volt supply.
the TPS may have been the cause, but other sensors share the +5V common supply.
The other sensors are Crank position sensor, MAP sensor and the TPS.
Since they are all there in the rear area driver side of the engine,
I would look there for a chafed wire harness.

[4.3LXJ]

What was that you pulled Tony/

[OldFaurt]

Well check this out...

https://youtu.be/C6pDhW1287M

Um... isn't that the air bag connector?
If it's doing that, the clock spring wiring is shorting out!
Careful! That can get exciting!
Air bag clock spring (http://www.ebay.com/itm/Jeep-Cherokee-Wrangler-1997-2001-Air-Bag-Clock-Spring-Dorman-525-118-/152210331845?fits=Make%3AJeep%7CModel%3ACherokee&hash=item23707158c5%3Ag%3AcPgAAOSw-itXtZ5W)

[Mudderoy]

What was that you pulled Tony/

Air bag :S

[4.3LXJ]

I would agree you have a problem with that module or circuit

[Mudderoy]

I would agree you have a problem with that module or circuit

Clock spring has a fault Steve, needs to be replaced, but that's been an issue for a couple of months, not something that just happened.

[4.3LXJ]

Could it have gotten worse? Putting that fuse in does make a difference

[Mudderoy]

Could it have gotten worse? Putting that fuse in does make a difference

Fuse? I think that connector made the connection between the airbag and the clock spring. Since the problem is the clock spring, my assumption is a connection issue between the airbag and the computer disconnecting the airbag from the clock spring seems redundant! :D

Of course it is just an assumption, which is probably why it's hard for me to understand how one thing would have anything to do with the other.

[4.3LXJ]

I have never understood the fascination Chrysler has had with that clock spring. Why that should be such an integral part of the ECM and dash operation is beyond me

[Mudderoy]

After disconnecting the airbag...

https://youtu.be/IzvD-Kq6SKA

[Mudderoy]

And for it's next trick!

The p0123 cel keeps coming back. Must be the clock spring...

We get a call, the 99 died on my daughter on the way to work. She was trying to start it in drive, told her to put it in park or neutral. Started right up.

She brought it home. I couldn't find a problem. Told her to drive it, might be the CPS. She's only about 3 miles to work.

She's backing out and I hear the rpms drop and raise. I signal her to come back in.

I try moving the steering where back and forth rapidly while its at idle.

The rpms drop, the rpms rise, they are now about 1,000 rpm. The CEL light comes on. F**KING clock spring!

Now I have a hint of yet another place I could put a kill switch on a Cherokee.

Clock spring disconnected! Runs fine.

So if you've been keeping score the $137 TPS I got from the dealership wasn't the issue. And it won't be for a long time ;)

Oh ordered this replacement from Amazon. Says it won't fit but the bazillion reviews say it will.

http://amzn.to/2oS1Apv