My 94 Plymouth Voyager (4 cylinder) temperature occationally indicates overheating condition, maybe on 1 out of 10 trips. Most trips ,25 miles or so, are without event, but sometimes after 5-10 minutes or so the temperature gauge pegs and the gong goes off. After 1-2 minutes the temperature gauge returns to normal and doesn't indicate overheating the rest of the trip.
So far, this is what I've found out and what I've done to resolve the problem. I've discovered 2 sensors that are involved.
There is a temperature sensor, ACDelco part # C1860, located on the lower portion of the block just below the second spark plug. This part is about 2" long and has a single screw terminal at the top with a single wire connector which can be pulled off. Cost $13.99
See
http://www.acdelco.com/html/catalog/index.htm
This sensor drives the temperature gauge and does NOT drive the fan. The wire, when grounded , will peg the temperature gauge but the fan does not come on.
The second is a coolant sensor, Mopar # 33004281, located just below the thermostat behind the igrition coil. This part is also about 2" long but has a locking device on a 2 wire connector. Cost $58 at dealer and $14.95 on Web. See
http://www.xtremeterrain.com/p90.htm
This sensor drives the fan via the relay circuitry. When this connector is unplugged, the low speed fan runs, although the check engine light show code #22, coolant sensor "out of range or disconnected". I don't believe this is a problem but looking for comments.
As a side issue, the relays are located in a box on the driver's side wheel well under the hook. The "box" is about 3" by 4" with a locking tab. On the inside cover is shown the relay identification and fuse location. When looking from the front of the van and directly over the computer box, there are 2 columns of relays, the left has 4 relays and the right has 2. The radiator low fan has a 25 amp fuse.
Computer, Relay and Fuse Box
----------------------------------------------------------
|
| FUSES including 25 amp low radiator fan fuse
|
| High Fan Radiator Ground Relay
| Fuel Pump Relay
| Low Fan Radiator Relay Air Cond Clutch Relay
| Auto shut down Relay High Fan Radiator Relay
|
|-----------------------------------------------------------
Front of Van
At this point I'm operating with the temperature sensor connected, (temperature gauge operational) and coolant sensor connector unplugged which causes the low fan to run when the engine is running and living with the check engine light, code #22. This is a cheap fix and may indicate a bad coolant sensor, and I need to replace it. If the overheating reocurrs, I'm planning on looking at the temperature circuit for bad temperature sensor or bad temp gauge. Comments?