There is no overheating problem. As soon as I turn the key to ignition ( Engine is not cranked yet) the Coolant temperature goes to High. When I turn on A/C, radiator fans work, there is sufficient coolant and Radiator cap looks good. I disconnected the sender transmitter plug(one wire plug) and gauge indicates low. I thought the coolant sender was acting up/grounding, so I replaced the sensor and it is doing the same thing.

Looks like the sender wire is grounded, if that was the case, when I disconnected plug from the sender shouldn't it read HIGH? If the wire is grounded somewhere then when I lift the connector that plugs into sender unit , it should read high also.

 

Hey guys, can someone help?

Some more information.

When I lift connector off of sending sensor...the gauge reads... low(cold)

So I thought the sending unit is bad. I replaced it with new one and still the same problem ... When I connect sensor..the gauge reads HOT even if the engine is cold.

It's possible I have problem with my gauge in instrument panel. It is hard to believe the gauge will go bad though.

If there was short/ground on the wire when I disconnected sending sensor then it should have read HOT. Right?

 

At gauge, check ohm resistance between Yellow/Green wire and ground. Should be 160-240 ohm at 122F, 17.1-21.2 ohm at 248F.

Check ohm resistance of brown wire(s), should be 0 ohms as they go to ground.

 

I have stripped screw so I can't access my gauge cluster right now. Here is what I did today, I connected one end of 50 ohms, 100 ohms and 250 ohms resistance to sender plug and other to ground. The gauge read HOT under three different resistance conditions. Instead of sensor I used resistance.

When I disconnect the plug at the sending sensor, gauge reads COLD. Seems to the problem is with gauge. Isn't it? I also checked voltage between ground and sending wire at the plug and it read 11.5 volts.

 

I was able to get my cluster panel out. The first wire which is yellow/green goes to sending transmitter. I unplugged the sensor connector and checked the resistance to ground. It was OPEN. That means the wire is not shorted or grounded. I then checked the continuity on this wire between cluster connector and sensor connector. It was less than 1 ohm.
I then plugged sensor and checked resistance to ground on the back of cluster panel it was reading 650 ohms when engine is cold. It is the same resistance I get when checked sensor to ground.

At 650 ohms, the gauge should be no where near HOT. Seems to me a gauge problem, isn't it?
If I changed out with cluster from ebay, what happens to the odometer reading? Is it in computer or it stay in odometer chip?

 

Does appear to be the gauge. The cluster stores the mileage reading.

Also try Amazon for replacement cluster.

There may be a way to replace the gauge but it may take effort.

 

Thanks Toyo

Before I buy a cluster, I want to ensure the resistance value I see from a sender is within range. You never know about after market parts. I get 650 ohms at the back of gauge, the same value I get right at the sender with plug disconnected. At 650 ohms there is no way gauge should read past COLD let alone HOT.

Is there any recommend buying from Amazon? I'm not sure about return policy on Amazon, Ebay sellers can accept returns if it is mentioned. Also I'm looking for gauge with little more miles than I have. I don't know if there is a way to program odometer.

I couldn't find a chart that shows resistance at different temperatures. I found one for the ECT but not for the gauge sender.

 

If you still have access to resistors find one(s) to approximate normal operating temp which is around 190F. Plot the two sensor resistance numbers provided and make a best guess of the resistance at 190F. Then determine if gauge is someone near normal temp indication which is typically just below the mid mark on the gauge.

Also check ground wires at gauge.

No recommendation of Amazon, just that the site has listings for a gauge of your year and model.

Have know owners to take apart the cluster gauges to mod them. You might be able to replace the gauge in the existing cluster.

Water temp gauge receives DC power from Red/Blue wire coming from Gauge fuse. Make sure voltage at wire and gauge is same as battery voltage.

 

So I bought the gauge cluster from Amazon and it is still the same problem. Temperature gauge pegging out. I'm run of ideas to check. Very disappointed.

Anything else I could check?

 

Do all other gauges work OK? If so then problem may be external.

Find wires for gauge at gauge harness plug.
Brown = Chassis ground
Yel/Grn = Gauge

Take note, there is more then one Brown and Yel/Grn wire. One Brn wire goes to tach. Yel/Grn to tail/brake light failure sensor.

After finding right wires, remove wire from plug and connect pins on console to chassis ground and gauge temp sensor accordingly. This to bypass all external wiring.