Throttle Position Sensor Issues, '91 Ho

[gogmorgo]

The MJ was idling unevenly and the transmission was shifting like I had my foot planted to the floor yesterday. If I don't keep my foot on the gas when pulling up to a stop, it'll stall. This morning it threw a check engine light, code 24 for the TPS. I looked around online, found some testing procedures and tried em out.

Probing the unplugged connector with the key on, engine off, I got <10Ω to ground, (pin closest to the passenger side) . I got ~4.8V between ground and the pin on both of the other two pins. All grounds were done to the neg battery terminal.

I also bench tested the TPS... It seems alright in that I get ~1500Ω to ~300Ω with a reasonably linear transition as I turn it up. I only tested with a digital multimeter, though.

 

I'm thinking my issue lies in the fact that I'm getting voltage from the middle pin of the connector. From what I've found online, I should be getting 5V from the feed line (driver's side pin), but I haven't found anything clear about what I should be getting from the signal line back to the ECU (middle pin). My mind tells me I shouldn't be seeing voltage at both points, though.

[gogmorgo]

Well, I caught a buddy with a '95 XJ, and measured his connector for comparison, and it was exactly the same. As much as I don't like replacing parts willy nilly without knowing they're bad, I'm about to go get a new tps. My buddy was in a rush to get somewhere so we didn't try swapping his into my MJ. Also, I put the multimeter back on my tps and got inconsistent results

...so, yeah. Fresh parts.

[HOrnbrod]

I still have my original TPS as it's never gone bad, at least in the 12 years I've had it. I've switched it around to different throttle bodies, and cleaned it up a few times, but have not had to replace it - yet.  :dunno:

 

Take care to salvage the gasket if you can - they are hard to find.

[gogmorgo]

Well, the new tps seems to have done the trick, but the BWD one the part store had looks like a piece of poo compared to what I'm assuming is the original that I pulled off.

I grabbed the gasket to put it on the new tps, but there was no provision for retaining it, and I didn't want to damage it so I left it off. Also, the "snout" on the new one seemed to be the same length as old one with the gasket. I'm hoping the gasket isn't crucial in a temporary sense. After a few paychecks this summer I'm going to get a Mopar tps because I don't trust the longevity of this one, so I'm hanging onto the old one and the gasket for the time being. Keeping the gasket on the old one seems like a decent way of not losing it.