I have a 96 Dakota sport with the 4 cylinder 5 speed. My truck has been over heating and my oil was milky so I thought it was a blown head gasket but also my radiator fan isn’t turning on. I’ve tried checking fuses for it but they all good. I’m just wondering what y’all think could be the problem before I go and replace my temp sensor. (Also my temperature gauge doesn’t work.) I have had a lot of problems with the electrical on this truck. My windshield wipers only work if I hold the fuse in. My right turn signal doesn’t work. I believe the fuse box needs to be rewired but if that doesn’t need to be done then I don’t want to do it.

 

Before anything, make sure that there is coolant in the system. If it's too low, it might not touch the sensor and cause the fan to remain off.

I believe your engine has 2 temperature sensors, one for the ECM (that would control the rad. fan) and one to control the gauge on the cluster. It would be strange to have them both fail at once, unless your temp. gauge hasn't worked for a while. First, try swapping your starter relay with the fan relay, they should be the same, and now if your starter doesn't work, you know the relay was bad. If it still works, try pulling the radiator fan relay and put a jumper wire between the bottom, vertical slot and the top, horizontal slot in the fuse box. This should turn on the fan. If it doesn't, then your fan is bad or there's a wiring problem. If it does turn on, it's probably a safe bet that the temp. sensor is bad. If you have access to an OBD scanner that can read live data, you can see what the ECM is reading the temperature as, and see if it's working or not.

 

The coolant is full and I switched it with the fuel pump relay and it still worked. The temp gauge has been out sense I got the truck back in the summer. I will try doing the jumper wire you suggested later today. Also my obd2 doesn’t work when I plug my scanner into it it doesn’t connect or get power but when I plug it into my other car it does, so I know it works. I checked and changed the fuse for the cigarette lighter and still nothing so could that be a wiring issue?

 

That might be a wiring error.

Good news! The factory service manual is available as a download from a link here (in the FAQ).

RwP

 

I have a power probe and I was wondering which is wire is the hot wire so I could just use my power probe. for my radiator fan.

 

Good news! The factory service manual, complete with wiring diagrams that include wire size and color(s), is available for download from a link in the FAQ!

RwP

 

I believe, in the relay socket, the bottom (vertical) slot is the full time power, the top (horizontal) slot is to the radiator fan, and then one of the side (vertical) slots is ignition power, and the other side (vertical) slot is ECM controlled ground. The middle (horizontal) should be empty.