Throttle position sensor acting up after replacement: Wiring Issues?

[troyston]

A few weeks ago I had a crank/no start (and then intermittent stalling) issue that I resolved by replacing the TPS and cleaning up some ground leads. I wasn't quite certain I was out of the woods yet, but it drove fine for a couple of weeks. Today it just stalled twice at intersections around town. It sounds like its running kind of rough, possibly missing, but no codes for that or indicators. I pulled P0123 (TPS High Voltage) and P1391 (Intermittent CMP or CKP) from the OBD right after. Tested the TPS and the sweep voltage is good, doesn't appear to be any issues — except here's where things get weird.

I pushed down on a conduit (around S-127) and noticed the signal voltage coming from the TPS dropped to 0 on my multimeter whenever I did it (red to signal wire, black to battery ground). Sounds like a short, but when I turned the key off and tested the resistance it went from what I would assume is normal (0.966kΩ) to 0L, or no connection. When I started it up, it ran ok, but when I started pushing down on the wire it seemed like it was missing again (but no new codes). Also one of the times I started it up, I forgot to plug the TPS in and it seemed to be running fine, when I plugged it in it started and idled rough. (even though I verified the TPS was working.

When I tore off all the conduit and electrical tape around, I noticed that a bunch of the sensor ground wires were bunched up, and then all converged on one splice in the wire, and then went back to being their own individual wires. After taking the conduit off, I haven't been able to recreate the dropped connection yet.

I haven't tested the CKP or CMP yet (mostly because I don't know how), but I did verify that they're getting 5v supply and have a good connection to ground that isn't affected by me wiggling the wires around.

I don't really have much mechanical experience at all, but any suggestions on things I could do with basic tools would be really helpful.

Here are some pictures of what I mean by the voltage dropping, I'll upload more tomorrow of the wires and all that.

 

[troyston]

 

[Chris]

I'm about to ask you the most important question of all:

What brand of replacement TPS did you use?

 

[troyston]

I'm about to ask you the most important question of all:

What brand of replacement TPS did you use?

It was one I picked up at O'Riley's, not sure of the brand. I've heard stuff about those causing issues, but it was sending a good voltage sweep (0.907 at idle to about 4.1 at full throttle and a steady rise and fall using an analog), and it also had a good sweep when I took it out and used my ohmmeter. I still definitely need to replace it with an OEM one at some point, but I'm not sure that it's causing the issue right now.

 

[Chris]

It was one I picked up at O'Riley's, not sure of the brand. I've heard stuff about those causing issues, but it was sending a good voltage sweep (0.907 at idle to about 4.1 at full throttle and a steady rise and fall using an analog), and it also had a good sweep when I took it out and used my ohmmeter. I still definitely need to replace it with an OEM one at some point, but I'm not sure that it's causing the issue right now.

There you go. I'll bet dollars to donuts that's your issue.

It's a very well known fact amongst TJ veterans that these things do not like any other sensor other than OE Mopar units. They are known to cause issues like this, so I'm not the least bit surprised to be hearing about this issue.

While there is the possibility it could be something else, Occam's Razor would tell you that the smartest decision would be to eliminate the simplest possibility first, which in this case is putting in an OE Mopar sensor.

Read around the forums and you'll see this is a very, very common issue. It's not just the TPS sensor either, it's ALL the sensors in your vehicle. Never use anything other than Mopar replacements.

Again, I'm almost certain this is your issue. Those ching-chong Chinese sensors just don't place nicely with these things.

Your story is so similar to many others. They bought a cheap sensor from the local auto part store, it worked for a week or so, but then the problems started happening.

 

[troyston]

Just ordered a new OEM TPS from the dealership but it's on back order and it'll be about a week. Any suggestions in the meantime as far as drivability/things I can test? If I put the new one in and the problem persists, what would you recommend to try next? Luckily I'm within walking distance of work but it would still be nice to have a vehicle.

Will definitely update when the new one comes in.

There you go. I'll bet dollars to donuts that's your issue.

It's a very well known fact amongst TJ veterans that these things do not like any other sensor other than OE Mopar units. They are known to cause issues like this, so I'm not the least bit surprised to be hearing about this issue.

While there is the possibility it could be something else, Occam's Razor would tell you that the smartest decision would be to eliminate the simplest possibility first, which in this case is putting in an OE Mopar sensor.

Read around the forums and you'll see this is a very, very common issue. It's not just the TPS sensor either, it's ALL the sensors in your vehicle. Never use anything other than Mopar replacements.

Again, I'm almost certain this is your issue. Those ching-chong Chinese sensors just don't place nicely with these things.

Your story is so similar to many others. They bought a cheap sensor from the local auto part store, it worked for a week or so, but then the problems started happening.

 

[Chris]

Just ordered a new OEM TPS from the dealership but it's on back order and it'll be about a week. Any suggestions in the meantime as far as drivability/things I can test? If I put the new one in and the problem persists, what would you recommend to try next? Luckily I'm within walking distance of work but it would still be nice to have a vehicle.

Will definitely update when the new one comes in.

I'm not sure what else you could do in the meantime. You could try other brands of TPS units if any local places have them in stock. Eventually you may find one that works, but it's a crapshoot of course.

 

[troyston]

On second thought, I noticed the airbag light is on for a few seconds longer than other lights when I turn the key on and my turn signals are acting funny (staying solid on when the brake is pressed). Any way this could be clockspring related?

 

[michaelwr80]

Just ordered a new OEM TPS from the dealership but it's on back order and it'll be about a week. Any suggestions in the meantime as far as drivability/things I can test? If I put the new one in and the problem persists, what would you recommend to try next? Luckily I'm within walking distance of work but it would still be nice to have a vehicle.

Will definitely update when the new one comes in.

Did that OE Mopar Part do the job? I'm having similar issues with my 98. I'm getting ready to purchase the tps through autozone, or do I just go ahead and spend the dough on the mopar part?

 

[troyston]

Did that OE Mopar Part do the job? I'm having similar issues with my 98. I'm getting ready to purchase the tps through autozone, or do I just go ahead and spend the dough on the mopar part?

My issue actually ended up being the Crankshaft Position Sensor. If you have a fancy scanner you can figure that out pretty quickly by reading voltages from the sensors (mine never threw a code), but if you're broke like me you can do it the long way with a voltmeter (

) before actually shelling out the money for a sensor. As always, try and only use OEM if you have the option.

For the TPS I would reference this video:

And weirdly enough, the turn signal issue I was having was due to my dog chewing up the trailer wiring harness and causing them to have wires touching each other making my turn signals and brake lights do all kinds of weird stuff. Any time you're having electrical issues always check all your grounds and make sure it isn't just something weird like that (wasn't the cause of my stalling issue; pointed me in the wrong direction).