BoundForGlory

Thanks!

Down by Mineral Point myself

Year, Make, Model. 1989 Jeep Comanche Pioneer 1994 block 4.0 running renix system, ax15, np231, Dana 35 with 3.07 gears, lwb Build date: completely rubbed off Current Location: southwest WI Status: Lived a long hard life, but still running and driving . Front brush guard that I can’t quite identify, aftermarket front and rear bumpers, exterior is primarily red, with pioneer graphics. Cloth bench seat, no read rests. Factory automatic truck? Still has column shifter, converted to an ax15 from a 1991 XJ Current owner: Me

Just fyi, my Renix system is running properly without the coolant temp sensor, based on that default Intake Air Temp + 1degree per 85 crank revolutions, so if your thinking it’s causing your hard acceleration cutoff thing, maybe just try unplugging it?

Looks real easy, for me, it’s a bit of an issue because I don’t have the right size square wrench (8mm square drain plug) but for you, if there’s a sensor in there, it should unscrew with a wrench. As for locating it, look for the drivers side motor mount, it is directly above that. The replacement sensor that I have uses a 3/4in wrench to tighten/loosen Nothing should need to be removed to get to the plug, but maybe jack the truck up to make it a little easier to see. Of course radiator fluid is going to come out, so cross that bridge however you wish.

No kidding, we shall see what the block has in store, and yes, the temp sensor wiring comes from the same harness as the o2

Man, that really clears things up, block code is 401MX20, so a 1994 obd1 block, and I’ve got a plug in the exact spot that fiatslug’s photo shows the sensor! Problem solved by the looks of it, now to get this plug out… Thank you guys for all for the help!

I did a little more looking, and the mystery plug is for sure the one for the ecu temp sensor. I plugged in my spare temp sensor again, and no matter how long engine idled, the ecu readout continued to read 72 (ambient air) - after considerable cleaning, the wires appear to be the correct color. Step 1, down. so… problem solved, and I have the proper temp sensor, but my block doesn’t appear to have any place for a sensor drilled. Block code is 53008-05, so 1991-1994? I think? Here is a photo of the block, drivers side, towards the front where presumably the ecu water temp sensor should be: Am I just looking in the wrong spot? According to what I can find online, the ecu was supposed to get its reading from the thermostat housing, but that doesn’t have a place for the sensor, the truck must be running the old renix housing? Could I just swap housings and extend the renix wires to be done with it? That Renix manual is really something! Thank you so much for pointing me toward that, it really cleared up my confusion on the readout, never in a million years would I have guessed that it goes up by 1 degree for every 85 revolutions when nothing is plugged in!

I’ll get er added to the registry when I have a little daylight tomorrow! As for tonight, I couldn’t help myself from trying unplugging that sensor to see if anything would change on the monitor, and, nothing. The sensor reads 69 degrees still, same as air, and warmed up to 75 degrees after a few seconds of idling. Is that sensor for the idiot light or the ecu? Because I’m concerned about the ecu readout that I’ve got, which I thought was supposed to come from the engine block, but of course, HO block, there is no place for one. I’m just completely lost as to where this readout is coming from, maybe it’s just a weird renix thing that is causing my monitor to freak out because no sensor is installed in the block location? I’ll check out some more stuff tomorrow, but for now I’m at a total loss

Sweet! I’ll start doing my homework, the back brakes on this truck are shot, so probably as good a time as any to bite the bullet

That’s why I’m here lol, totally new to these things! I appreciate you letting me know, maybe time for some reading on an 8.8 swap

I’m so glad I found this forum, what a wealth of information! (I’ll check this in at the vin registry once it gets light out) Here she is! My 1989 pioneer with a 4.0, ax15, 4x4 and some 35 inch tires! And what appears to be 3.07 gears… I saw the machine during spring break, and after convincing my dad to drive 4 hours each way with a trailer, I went up to get her. About that trailer… thought it was rated for 5000lbs, but some bottomed out leaf springs were screaming otherwise. Oh well, at least it’s easy to unload, the 35s just roll right off! Anyhow, at this point, it’s 8pm, and there’s a snowstorm moving in/already here, but I had faith, in this new to me rig, and set off into the night, with my dads watchful eye behind me in case a wheel flew off or something. Now, the previous owner had told me two mission critical things: #1 - the radiator leaks, and #2 - the temp sensor jumps up to max and stays there, so the Renix engine monitor is no help in this case. But hey! At least it has an engine monitor! Having to refill the radiator made for slow going, and the lack of a temp sensor led immense amounts of stress, but we made it! My roadkill-style mission actually turned out better than expected. When all was said and done, I was down 3 cans of radiator fluid, got pulled over 2 times, and had 1 sweet project sitting in my yard! (I think the cops were impressed, despite being down both a headlight and a taillight in the dead of night, one just talked to me, the other gave me a written warning with no fix it ticket and told me to wave it if other ones pulled me over on the rest of the way). Now it’s here and it’s mine, and I’m on summer break so it’s time to get to work! What I know so far about it: started life as a 1989 pioneer with an auto trans previous owner installed 1991 xj axles, transfer case, transmission, and engine, but it still runs a renix ecu. So far: New NTK o2 sensor Headlight relays And a whole lot of figuring out where wires go and how this thing is set up. Radiator fixed To do: -cupholder -Temp sensor -get rid of that window tint -hook up speedometer -Hook up reverse lights -Pound out a ton of dents -rockers down the road, and maybe some kinda rock slider -touch up paint -Maybe put a Dana 44 on the rear end… But then, I looked under it today, and HALLELUJAH! Beneath that caked on mud and rust, I’m pretty sure that’s a 44! I’m loving this truck so far, but man, there’s a long way to go! Hoping to keep the truck along similar lines as it’s already on, just a fun off-roader jeep, and really put my effort into making it super reliable.

I am beyond lost on this one! Just a new guy trying not to burn his truck up! A little backstory that might help things, otherwise I’ll put a TLDR at the bottom I’ve got my first Comanche, which I bought over spring break, but haven’t had time to dig into for a while. The truck has a 4.0, ax15, transfer case, and axles all recently installed out of a 1991 xj, while the truck itself is a 1989. This wouldn’t be all that complicated if we were running the 1991 system, but nope! We’re on Renix, baby! So 1989 CPS, and everything is hooked up to that. Some other parts from a renix system are left over too, specifically the thermostat housing, so there’s nowhere stock to hook up a temp sensor. Despite this, the nickintime design renix engine monitor that came on the truck shows me a temperature readout, which starts at air temperature, and then creeps up to 248 degrees (the max temp it can read) and stays there, but the engine doesn’t boil over, making me guess a faulty sensor. Where this reading comes from, I have absolutely no clue. I have only found one temp sensor in the engine bay, and it’s on the radiator (open cooling system conversion by the looks of it). Here is a picture of the wires that it connects to (yellow and grey). They break out of the loom in the front, drivers side corner. But when I unplug it and turn the engine on, I still get a readout, which rises as the engine gets warm. No dice. As I looked around on the engine, I did find another mystery wiring harness break out that looks like it should hold a sensor, but if that’s the input, then how is ecu getting a temperature readout?! I did a little testing, and when I plugged in a spare, cold sensor into this plug on a warm engine, the sensor Renix monitor continued to read 248, so clearly this plug doesn’t effect that ecu, it’s probably for the efan? Which has never turned on for me. here is a picture of the mystery plug, on the drivers side of the engine block: And a picture of the wiring coming from the plug: The thermostat itself is pretty much new, and a leaky radiator verified for me that it is working (radiator only leaked when engine got warm). So, I’m pretty confident that my cooling system is good to go, but I could stand corrected. The truck survived an hour drive without boiling over, and the idiot light never came on for temperature, which I think is hooked up, but I could stand corrected on that too. TLDR: 1991 engine in 1988 Comanche, running a renix ecu, can’t find temp sensor, only one in engine bay seems to be on radiator, plugged into harness, but doesn’t affect the ecu. Readout on engine monitor starts off accurate, but quickly climbs to 248 degrees and stays there. Electric fan does not come on, may or may not be hooked up. Idiot light is hooked up but does not turn on even on 15 min drive. Any ideas as to where it could be? Could the Renix engine monitor be faulty? Do I just trust the idiot light and forget about it?