MorpheusGPR

I have grounded the wire and it maxed out at 299 degrees or something to that effect. I replaced the sensor in the head and the gauge still only reads "Lo".

I have read that air pockets may also cause this? I have burped a ton of air from the system without any change thus far.

jghmczo6

You may be receiving an error message from your ECM, especially if you have removed all the air from a closed system. Disconnect the negative terminal from the battery, wait ten minutes or so and reconnect the battery, should clear the error.

Hope this helps

CFI-EFI

huh???

Since the gauge goes to the max, when grounded, you know the read out and wiring is OK. About all there is left is the sending unit. Is it the right part? Could it be defective? You aren't preventing it from getting a good ground in the head by using too much Teflon tape, are you?

RACE ON!!!

SunCr

Assuming it's the '89 in your Profile, Ecm has nothing to do with the Temp Gage. Serial Data is only used for Mileage and Range. Grounding the wire should give you something north of 300. You need to ohm out the wire between the Sender and the Display - Pin D4 and make sure there isn't any resistance in the wire or a poor connector. Check/compare the ECT signal with a scan. Verify the Selection Switch is working - make sure it shows Battery Voltage when selected.

MorpheusGPR

I will take my teflon tape off and see if that does anything.

65Z01

If it is an '89, I assume you are talking about the sensor in the block below 68 & #8 spark plugs as that is the sensor that drives the gauge??

MorpheusGPR

Yes its an 89 and yes the sensor down by the oil dipstick

65Z01

I would not use teflon tape on the threads, perhaps a little anti seize would be enough and conductive too.

Also, measure resistance of that sensor cold & hot; resistance should drop significantly as it heats up.

jfb

Unplug the coolant sensor wire and connect a variable resistor from the green wire to ground. Varying the resistor will cause the dash coolant temp to vary. You can use a variable resistor of anywhere from 10k to 100k ohms and you can buy one at Radio Shack. If your dash temp still stays on LO, then you have a defective circuit in the cluster circuit boards and it will have to be sent to a service center.

CFI-EFI

The gauge reads 299, the limit, when the wire is grounded. It will work just fine after he gets that mile of Teflon tape off of there. *I* would use Teflon paste rather than the tape.

RACE ON!!!

MorpheusGPR

Thats what I was hoping for but no, not yet. I took the tape off, put it back in and still reads "Lo"

Just for curiosity I had my wife sit in the car and I took some pliers, pulled the connector off the sensor and found some metal to touch it to. She told me it was varying around on the temp reading going up and then down etc. I had touched the metal portion of the connector to the manifold.

Thats the only time I have been able to get any reading other then "Lo" or the max (when I grounded it).

Out of curiosity is anyone making a gauge cluster kit that can be put in place of the digital system? Maybe autometer or their competition?

65Z01

First isolate the problem area.

Try the variable resistor between the connector and frame ground; if the display responds focus on the sensor.

Next measure the resistance of the sensor (between the sensor tip and frame ground) as the engine heats up; if the resistance doesn't drop replace the senor.

BTW, are you sure you got the sensor and not the switch??

MorpheusGPR

Its got the same spade connector on it like the one I took out.

The unit I had in there was wrong and it went to the drivers side head. So that has been corrected I just need to re-wire what the previous owner did.

Its a brand new sensor I just put in.


I do not really have any experience using resistors.

jfb

Well, then get some, its easy as pie. Go to Radio Shack and tell them you want a variable resistor, anything from 10,000 ohms to 100,000 ohms will do. There are three terminals on the variable resistor and you connect one of the outside terminals to ground and the middle terminal to the green wire. Turn the ignition to run and watch the temp gauge while you slowly rotate the variable resistor. The temperature should go up and down showing that the electronics in the dash cluster is working properly.

MorpheusGPR

Ok I am on my way out to try and find the 3m adhesive remover I will try to find a resistor as well...sounds easy enough.

MorpheusGPR

I got a pack of 470k and some aligator clips to make it quicker. I am going to try it later when my wife gets home so she can tell me if the gauge is changing at all as I move the resistor around.

These only have two ends so they may not be right, but if I don't get the gauge worked out soon I am putting in an autometer gauge and using it.

65Z01

What you need is a variable resistor or a bunch of 10k 1/4 watt resistors.

With the latter, twist together the ends of say 4 of them and see what the gauge reads.

MorpheusGPR

Since I have these 470k can I use 2-3 of those and test it tonight? Otherwise it will be a while before I can get back to the store again.

65Z01

Yes, if you twist the ends of say 8 of those together so that they are in parallel, you will then effectively have 59k resistor, which may not be low enough.

jfb

470k is too high, you would have to parallel a bunch of them to get the temp gauge to change temperature reading. Why didn't you get a variable resistor? thats what you should have bought. Look at the gauge with the ign in run and start paralleling every 470 k resistor you bought and see if the dash temp gauge changes temperature.