1998 Dodge Neon Temperature Gauge

AMERICANBADASS

MEMBER
1998 DODGE NEON
4 CYL
FWD
AUTOMATIC
302,000 MILES

My 98 Dodge Neon Temperature gauge is faulty. When I turn the key it says that the engine is over heating, even before I turn on the car. I recently broke down, the temperature on the car read high and I immediatly pulled over to the side of the road. When I did pull over there was a smell of something burning. I then proceded to put water into my car and tried to turn the car on and the car wouldn't turn. It was too dark for me to diaganose the problem and another thing is that it was raining out. So I had leave the car and have it towed to Canadian tire the next day. I had them inspect the car which took them well over a hour and then they told me that my engine was fine but they couldn't figure out why the car still wouldn't turn. They then insinuated that perhaps it was the starter and a crack in the radiator. I went and bought a starter and when I was about to replace it I noticed that my ground wire was snapped off. So I replaced the ground wire and then went to take off the radiator and the plastic snapped. So, I had to replace it with a different radiator. I replaced all the fluids and then started the car. It worked! But, I noticed when I turned the key the temperature gauge was indicating that the car was over heating when in fact the engine was cool. I also noticed that the fans were not working. Even when I unpluged coolant engine temperature sensor the fans are supposed to automatically turn on they didn't. I was far from home and was desparate. So I then hooked up the fan that blows to the engine directly to the battery just to make sure I will not over heat. But the temperature gauge still indicates that it is over heated. What is my problem?

1 Reply

CARADIODOC

MECHANIC
33,871 POSTS

Dandy observations. Since the fans didn't come on when unplugging the temperature sensor, I would suspect the fan relay module. I have some good used ones here. By the way, did the sensor have two wires? If only one wire, that's for the gauge. You need to unplug the two-wire sensor.

There was a recall for the fan relay bolts breaking off. The relay must be bolted to the core support for cooling because the switching transistor passes full fan motor current so it gets very hot. When they fall off and overheat, the fan motor usually doesn't run, but I have heard of some shorting so the fan runs all the time. A shorted relay gets more than hot enough to burn your hands, (I found out the hard way!), So it might be possible that's what you were smelling getting hot.

Caradiodoc

Can you tell if the gauge needle is more than 180 degrees higher than "cold"? These gauges are not spring-loaded mechanical units like in the past. They have four coils of wire that are pulsed by the instrument cluster which is a computer module. If the pointer went well over 180 degrees, (I mean half of a full revolution, not temperature), the cluster is trying to pulse it back to "cold" and the shortest way there is to continue going clockwise. If it looks like that's what's happening, the dealer can connect a hand-held computer that will run all the gauges to various positions, then back to their lowest setting. If you want to tackle it yourself, you'll need to remove the plastic cover and physically push the needle back down.

If your gauge only has about a 90 degree sweep, I would suspect a problem in the cluster or something causing the needle to stick. You could try repositioning the needle, then watch what happens when you turn on the ignition switch. If it instantly goes to "hot", unplug the single-wire temp sensor and measure the voltage with the ignition switch on. It should read 5.0 volts on the wire when it's disconnected. If it reads 0 volts, suspect the wire is grounded. If it reads 5.0 volts and the gauge stays on "cold", suspect a shorted sensor. (That would be extremely rare). If you find 5.0 volts on the wire, which you should, and the gauge goes to "hot", the problem in in the cluster. I suppose you could try a different gauge in case one coil is open, but the cluster is the more likely cause.