p0117 - low input voltage for ECT - fixes?

had an elaborate and thorough post and then the power went out...

warning: slightly lengthy

98 Classic, 121K, k&n drop in filter, all stock

Before I had a problem w/ my 02 sensor(s), code was either p0107 or p0131... basically input sensor voltage low and/or sensor needs changing. Changed upstream 02 sensor, then the p0117 code came up bout' the ECT. Changed the thermostat and ECT sensor, broke the snappy thing that snaps the plug in place. (I'm thinking this could be the culprit, but I highly doubt it, fixes are never THAT easy for me ) It still plugs in fine, but it doesn't snap in place.

I tested the downstream 02 sensor and it passed fine. Tested the input voltage from the plug in to the ECT while the jeep was in the "on" position, it was getting the full 5v.

What usually happens while I'm driving is my temp. guauge will spike to the red zone, my check guauges light will come on, then it will go back to what normal temp. it actually is. Sometimes that happens several times during my drive, sometimes only once or twice. If it happens too much, my CEL light will come on. I check the code and get the p0117. Just this morning after gasing up the CEL light isn't on anymore, which is usually what it does.

I've checked the PDC for any blown fuses, couldn't find any. I haven't had the want to pull the wires along the fuel rail apart to check for a short, but if I must then I guess I will.

I've wasted $100 to get an engine diangnostic in which the mechanic told me he couldn't find anything new from what I already knew (the jeep wasn't running all crappy for him like it usually did for me) I've reset the PCM multiple times after checking both o2 sensors and the ECT and my jeep isn't running lean anymore like it was before, but this code keeps popping up and it's keeping me from my upgrades.

Sorry for such a lenghty post but any help is highly appreciated, maybe (most likely) I overlooked something?

Thanks

.... anybody?

"What usually happens while I'm driving is my temp. guauge will spike to the red zone, my check guauges light will come on, then it will go back to what normal temp. it actually is."

The temp gauge spiking kinda leads me to think you may have a loose wire somewhere. Did you double check all the electrical connections you worked with? It's a start. At least you can start eliminating possible sources.

Luck to you
chris

I too think it's a wiring problem. Since you're getting 5v to the plug terminal, I'd check the plug itself, and the wiring going back to the PCM. The ECT probably has a dedicated ground wire, so I'd check it for continuity with ground. That spiking temp gauge sounds like an intermittant ground.....

XJ Buzzard said:

"What usually happens while I'm driving is my temp. guauge will spike to the red zone, my check guauges light will come on, then it will go back to what normal temp. it actually is."

The temp gauge spiking kinda leads me to think you may have a loose wire somewhere. Did you double check all the electrical connections you worked with? It's a start. At least you can start eliminating possible sources.

Luck to you
chris

Click to expand...

could me installin' a new cd player mess w/ connections that would mess w/ that kinda stuff? I wouldn't think so, but it wouldn't be surprising. I'll have to check through that stuff since that's the only electrical I've really messed w/.

Runnin'OnEmpty said:

I too think it's a wiring problem. Since you're getting 5v to the plug terminal, I'd check the plug itself, and the wiring going back to the PCM. The ECT probably has a dedicated ground wire, so I'd check it for continuity with ground. That spiking temp gauge sounds like an intermittant ground.....

Click to expand...

I was thinking this as well... my only problem is that I don't know where the ground wire is for this sensor... I think most of the sensors share the same wire from lookin' at the wiring diagram, (I could be completely wrong about this though)...

Thanks for the replies!

My next question would be if anyone possibly knows where the ground is for, well... any of the sensors?

Personally, I would take and trape or some other way the conector going to the ECT. that way you can totally get rid of that being a possibility.

Im not sure, but if the ECT gives info to the computer of temperature, that could chand A/f ratio and a bunch of other things.

My next question would be if anyone possibly knows where the ground is for, well... any of the sensors?

Click to expand...

I took a look at mine, and it has a 2-wire ECT, with black and tan wires. The black wire is grounded (with the block) with the key off.

Don't know if this helps, mine is a 96, with OBD II, but your 98 sensor may be different......?

Many of the sensors ultimately ground to the bolt/nut that's near the oil dipstick. You might check that. I once found that bolt only hand tight on an XJ of mine. It caused me lots of grief and I was ready for the asylum before I finally found it.

I believe there is another ground strap at the back of the engine going to the firewall. Intermittant electrical problems are a muther to deal with. Make sure they are all clean and tight. The ECT connector may need to be fixed or firmly made to stay in place.

chris

Runnin'OnEmpty said:

I took a look at mine, and it has a 2-wire ECT, with black and tan wires. The black wire is grounded (with the block) with the key off.

Don't know if this helps, mine is a 96, with OBD II, but your 98 sensor may be different......?

Many of the sensors ultimately ground to the bolt/nut that's near the oil dipstick. You might check that. I once found that bolt only hand tight on an XJ of mine. It caused me lots of grief and I was ready for the asylum before I finally found it.

Click to expand...

thanks for taking the time. Sounds like for the most part it's all the same. I didn't know there was a ground bolt/nut near the oil dipstick so I'll have to take a look and see if mine has one in the same location.

Thanks for all the replies, I've been plannin' on tapin' that sensor and plug up so I could rule that out as well, just haven't gotten around to it... Also I'm wondering if should get some special kind of tape cuz of the location where I'm taping it at...

I'll keep an update or somethin, thanks!