Ok, I don't know where to go from here. I have tried what I know and can't find answers in the manual.

My car coolant temperature gauge is going crazy. It will rise to 3 O'clock and I'll look down and it'll be at the bottom of the scale like it's 90 degrees instead of 188 degrees. I can watch it go up and down several times while driving. Now the ECU is reading the correct temp like 182 to 215. I have a ScanGauge II hooked up to it and it will stay at 188 to 192 the entire time the car gauge is raising and dropping.

I'm thinking there is some loose ground for the cluster somewhere or something like that. Maybe I have a bad cluster. I don't want to replace the cluster for nothing. I'd like to fix the one I have, the miles are real close to the OBD-I port reading.

 

I can't help but think that this and your other (ambient temp reading) issue are related. Have you double checked that the cluster's wiring harness is plugged in tightly? Also check for corrosion or damaged terminals.

 

Have you changed the coolant temperature sensor (the one at the base of the thermostat housing)? I've had two go out in the last 7 years and one made the temperature gauge go all wonky

 

No I have not. The reason being, the ecu is getting a good reading all the time. So says my OBD-II Scan Gauge.

 

Along with the ambient temp issue your having, my thoughts is a wiring short some where before the cluster or you could have a cluster issue...

Do you have a blinking service light? not check engine but service light.

 

No. Everything else is rock solid. I'm considering getting a cluster from the yard, there is a R wagon there. If that solves the issue then just get the odo fixed and set the mileage to my current 204,000.

On a side note, they just crushed 2 850 wagons here. Both had super clear tail lights. I kinda wish I had snagged those for someone.

 

If you ever see a pair of tail lights that look in really good nick, grab them for me. I would prefer the v70 look ones, but clean 850 ones would be just as good, because mine are all hazy and cracking.

 

Those things were like new. My guess under a year old. I'll let you know next time I see a set.

 

Well, I got a used ignition switch yesterday and thought it may have been newer than mine but it felt weak compared to mine once I installed it. Maybe mine had already been changed somewhere along the line.

Drove 2 miles to my PO box, left the car running, and when I got back in it, the temp gauge was down to low. When I started driving it went back up so I'm guessing it's not the ignition switch.

My next move is to clean ground wires in the engine compartment.

 

If your ECU (via the OBDII live data) is saying the temp is constant, or at least does not agree with the interior visible gauge, then the problem is between the ECU and the gauge. If all your other cluster lights and gauges work then the cluster has a good ground.

Being that the coolant temp and ambient temp (which you mention in another thread) signals go through the same harness connector into the gauge cluster, I would suspect that connection first. You could pull the dash pad and wiggle the harness connector, see what happens.

 

I guess. I'm trying to remember if I had the thing out lately. I guess not. I did have the dash pad off, I replaced that.

I'll lift the dash pad and play with wires. I'll unplug one side, then the other, then mess with wires one at a time.

I'm starting to think I have a bad cluster. I had a spare cluster here a few days ago. I should have tossed it in and drove around a day or two with it. When I went to the jy the other day the cluster was gone from the '96 R that is there. That's the car I got the ignition from. I swapped that igntion back out, it was toast.

 

RSPI- My local u pull it has a wagon with nice shiny tail lights, but the place charges a buck an inch for tail lights. I could buy new ones on ebay for a little more than that. I've sanded and polished my left lens, used a little polishing compound and finished it off with some clear spray. They look pretty damn good for 0$. Thats usually the way I try to do it. Got a perfect straight, no rust fender there last weekend for $32. (rust free is unusual here in upstate NY) And the car was a 93! Sometimes I think folks forget about junkyards. Dave

 

I'm still chasing this problem and was trying to make sure my instrument cluster was getting good power but none of my fuses power it. Does anyone know what fuse or relay powers the instrument cluster?

I pulled ever fuse out of the fuse box and the cluster still works.

 

Well, I ordered a temp sensor and pulled the cluster to see if I could see a problem with my ambiet temp gauge (I was going to swap the trip computer) and I think I found my issue. It seems that the wire plugs on top of my cluster assembly has crimpted wires on top of the plug. I moved the wires a little on top of the plug, hooked everything back up and I have had ZERO issues with my temp gauge now. Also, my ambient temp gauge is a lot closer.

So I pulled a (cut) harness from a car from the yard and I'm thinking about splicing it in and seeing what will happen.

What is the best way to splice that plug in? There is about 16 wires.

 

Shared my delima with my wife and she said there has to be an end to this plug. So I called the stealer and they said that it is a branch off of a bigger tree, part of the "behind the dash harness", $748. So the wife goes... "How much did you pay for that car again?" (Very funny!)

So, I'm back to my last question, what would be the best way to splice 22 wires?

 

If you're planning on removing it anyhow, first try to pry the connector apart and re-work it. I have refurbished plugs when faced with the same situation you have. An electronics store may even be able to help you find specialty wire terminals that fit in the plug, so you can just cut the wire back a little and re-terminate.

I don't like splices, especially when we're talking about wiring for gauges that work on resistance.

 

I'm with you. I don't like splices either. I got a plug from a car in the junk yard to see if there is a way to repair a few wires and it doesn't look easy. Also, I don't think I can shorten any of the wires on the harness without making them prone to brakeage from stress. I guess I can add a little wire to any that are broken but it will be hard to figure out which 3 or 4 of the 22 wires are bad.

 

Ya know, the first thing I would try is to put some electrical connection grease in the plug and put it back together good and tight, see what it does.

 

Everytime I plug it back in something else doesn't work. Now the trip computer mileage doesn't work. Only tells me temp and gallons remaining. I don't think you understand about my harness wire damage. It's like the wires are broke within the wire coating. When you look at the wires, you can see that some of the wires are hanging by the wire coating.

 

LOL, to my surprise, my cruise stopped working. Not sure how many days went by before I realized it but it's not working. Also, my trip computer wasn't working and my OBD-II port had no speed signal.

It's all fixed now. I'll give you guys the shortest version that I can...

Over the past year (not sure beyond that, just got the car in May 2011), the ambient temp sometimes showed LO and just got worse over time and at the end was showing temps all over the scale, mostly low. I believe this was fixed by pulling the cluster and heating/sweating every soder joint I though mattered. I heated/melted about 30 joints and added a little soder to a few joints to make sure it had enough. The ambient temp is dead on 100% of the time over the past 2 weeks with no LO reading. A LO reading was normal to see at least once per day. My guess is that I drive about 10 trips per day.

As for the other problems, I believe it was caused by the aging, damaged wire harness. The engine temp gage and very rare fuel gage in accuracy was solved by replacing and splicing in another wire harness from a donor car. Just a note, a '96 harness was missing 1 wire that I needed so I had to get a harness from a '95, use the same year harness if you ever do that. There is a slight chance that my coolant temp gauge accuracy was improved a little with the soder joints sweating.

As for my cruise problem... When I spliced the wires together at the top of the cluster harness, one of them pulled loose and stopped the speed signal from going from the cluster to the cruise and ECU. They both get their speed signal from the cluster.

On to my power steering leak...