ArmyVet717

Ok, so I was planning a little trip to "explore" around Mt. Hood, but 2 new issues came up...
1. VIC: "Coolant Sensor Bad"
2. VIC: "Rear Lamp Failue"

So the coolant sensor was replaced a few months ago (October or November), and the "rear lamp failure" started the other day after I switched the plugs on the VIC since having the 242 put in. But then it stopped and then today, out of the blue, just started flashing. Tail lights, turn signal lights, brake lights, and reverse lights all working fine... So I am really lost on this one. Not sure why that would be flashing if all my lights are working...

Thanks for the help...

dave1123

There are 2 coolant sensers. One is for the guage and the other (on the 4.0) is under the intake manifold and is for the ECM. I changed 2 guage sensers before I found the other one.

If you have the tow package, there might be a problem with the unit. It's located behind the drivers side tailight inside the cargo area.

ArmyVet717

I have the 5.2, and I know the one on the block was changed. And according to the VIC, it is on the front of the vehicle. At least, that is where the rd light is flashing... I know sensors go bad, but it is only 4 months old...

dave1123

Is there one on the thermostat housing? That's where my guage sensor is.

tiwvr1

Two things. my 94 zj flashed coolant temp sensor, it was the sensor IN the overflow bottle, and it wasent bad, the coolant was just low. That is all it is. The sensors on the block, one is for gauges only, and the other is for pcm only, nothing for the vic. Check coolant in resiovor, u will see the sensor in there.

Second, make sure that all THREE bulbs in the third brake light are working, if they are it could be the lamp outage module, open your hatch, on the drivers side, behind the plastic panel is the lamp outage module, worse comes to worse you can un plug it and connect the harness. but then it will flash tail lamp failure all the time.

ArmyVet717

tiwvr1: Thanks for the info!!
I know that the one on the thermostat housing was replaced, but I did not know that there was one in the reservoir. I will check that first thing in the morning. I just had the radiator flushed, but I have also read where there is a problem with VIC circuitry or soldering points. But, I got's to start somewhere, so the reservoir will be the first place I check...
As for the lights, I will double check all my bulbs again then the module. I just think it is weird that that started after having my TC swapped...

ArmyVet717

Okay, so I checked the reservoir that goes to the radiator and it is full of fluid. I started driving and again the coolant sensor bad started flashing as well as the rear lamp failure. Stopped at the bank, jumped back in and so far just the coolant warning is th he only thing that is going off... Lamp failure is gone now. What else could be causing the light failure light to come on??

tiwvr1

Im tellin ya, as far as i know from personal experiance, the one in the resiovor is what will cause this, try jiggling the senosr in there with something, try un plugging it, and then jumpering it to see if it goes out. just to see if that is the problem.

When my lamp outage module burnt out, it would only show a failure when the headlights were on, and the brakes depressed. I honastly wound worry about either of these items. if you do a search you will see how many other people have the same items come out.

tiwvr1

Here is a proven fix from another site

So the truth is: This message is generated by the coolant level sensor. It is directly wired to the VIC and the VIC is the only thing that uses it. So it really doesn't matter at all. It is just a dumb warning light.
Ok, so how do you fix. I'll bet most of the problems are exactly like mine, but I'll go over the easy stuff first. And Jeep should pay for it because it is a shotty manufacturing flaw. But before I reveal the secret, lets make sure your problem isn't a simple one.
Take the coolant level sensor out and unplug it. First test the sensor. Put an ohm meter accross it and when you push up on the float (as if there is plenty of coolant) it should read 3.3K ohms - or close to, mine is 3.2K. Then let the float drop and you should get closed condition (near 0 ohms).
Now put the ohm meter on the connector from the jeep. First connect it to the black wire terminal. And put the other side of your ohmmeter to a good ground (like the battery term). Should be close to 0 ohm.
Put the sensor back together and plug it in. Give a spray of contact cleaner while you are there. Under the drivers dash, there is a plastic cover near the ODBII connector. Pop it off. There is a orange and white connector that is fairly large, it has 20 wires I believe. Pull it out and find the pink with black stripe wire (same color as at the coolant sensor). Measure resistance between it and a good ground. It should be 3.3Kohm (as long as you have enough coolant in your reserve tank). Spray with contact cleaner and put back together if all is good.
Of course if any of the above is bad, fix the wiring or the sensor. But my guess is it is good. So here comes the fun part.
Tear apart the dash and remove the VIC. Look somewhere else for a dash removal inst. Basically remove the glove box and the panel around it and the panel around the VIC, with two screws behind the ash tray.
Unplug the VIC and take to the bench. Open it up (need torx bit). Get the circuit board out. On the connector - look for your pink with black stripe wire and match to the pin on the circuit board. Then look on the back and look at the solder joint. If you have a magnifying glass or good light - you'll probably see what I saw - a bad solder joint (cracked at the connector pin). Its neighbors may be bad also. Use a soldering iron and reflow with a little new solder. Do the others while you are in there. Put everything back together and enjoy beep-free driving.

ArmyVet717

tiwvr1:
Well, tonight on my way home from the gym, only the coolant sensor was beeping at me. So basically, since this afternoon, the light failure has not beeped at me, but the coolant one still is...
The other site you are speaking of sounds like jeepforum.com, LOL... If you look at my website, I have every forum I have found and am a member of on there... Great sources of info!!
The light failure thing I will work on when it stops raining, but as long as all my lights are working, I wont worry about it. But, other than earlier today, it has not come on. The coolant sensor is actually more important, but before I can fix the VIC, I have to go down and buy a soldering gun and solder... For some reason, I can't find mine... I just love moving, I lose more crap that way...

tiwvr1

yup, thats where I got it from. All i had to do was add some coolant to get mine to disappear.

ArmyVet717

I am going to keep my eye on it, but the reservoir is at the full line. May be if I add a little to it I won't keep hearing it.

I am a member every Jeep, Cherokee, and Grand Cherokee site I have found. Everyone has given me good info, I just get confused when I get more than one way to fix the same thing...

ArmyVet717

So, I have ben driving around for the last couple hours with only the coolant sensor screaming at me. Then, I hit the TC shift lever and the rear lamp failure started screaming at me... WTH!!! Lmao

ArmyVet717

Oh... ALL my rear lights are working. But, my TC selector light its out, could that be causing it??

tiwvr1

i dont think that will cause it, i think it is only head lights and tailights, I can check the wiring diagram on mitchell at work on thursday