please help with radiator fans!! Need to get to work!!

[nkbrkr2]

Ok, I have a 96 rt/10 and have been researching this since last night. I was driving to work on Monday and noticed that my car was almost at redline 250 and wondered why as it has never happened before. Got to freeway and rode about 2 miles or so and engine cooled back to 190. Got to work and noticed fan is not coming on. Drove home that night and took the Relays out and replaced them and got nothing. I hot wired the fan from the connector.. Works, took off relay, hot wired it fan works, jumped 3rd connector on PCM ground out 2 and 21 nothing just clicks. I am a bit baffled. I also noticed that the AC is blowing hot as well not sure if they are connected at all. Please help as I already missed today at work and in this economy cant really afford to miss more! Thanks in advance for any help.

 

[dave6666]

It sounds like your coolant is circulating based on the fact your car cooled on the freeway.

When you say your AC didn't work, was that on the freeway too? Because if you're sitting still and the fan no workie then the condenser is not condensing the Freon and therefore no AC.

If you can hear the relay click but no results there could be a few causes. One is there are 2 fuses, at least with my '01. A fuse for the relay hi-lo coil (although it would at least default to one mode or the other) plus the main fuse for the fan that also powers the fan on-off relay coil, and then there's the PDC itself. How did the relay contacts look when you unplugged the relays? Look down in the relay socket for burns.

 

[nkbrkr2]

relays look ok but the high low has an aftermarket relay already, must have happened before I bought it. The relays click when grounded out but dont turn the fan on. If I put voltage to the plug the fan will come on, so wiring should be fine. Im looking in the owners manual for fan fuse and dont see one? Could I be missing something??

 

[dave6666]

Are you putting voltage to the fan at the fan connector itself, or the PDC?

You should check the following:

-> 12VDC present at the PDC relay terminals to the relay contacts.

-> use your 12V source you are using to test the fan at the PDC also. The wires between the PDC and the fan could be bad.

Here's a pic of my '01 wiring showing the second fuse.

You must be registered for see images

 

[nkbrkr2]

Mine looks quite a bit different but I put positive to the connector directly at the fan and fan works. I took the relay out of the socket and ran positive into the socket and fan turned on. I took the 3rd plug out of the PCM and tried to jumper 2 and 21 which make the relay click but does not turn on the fan. So the wiring from relay to fan is good and works but the relays wont turn on. Even jumping from PCM to turn on relay manually doesnt work.

 

[dave6666]

Then do you have 12V at the relay from the battery? Like is there power to the relay contacts? Not the coil, the contacts. From the fuse/battery.

 

[nkbrkr2]

Is there going to be a constant supply if the car is on, and then the relay closes to turn on the fan when it is called for? Or do I have to get it to operating temp for positive to be on?

 

[nkbrkr2]

I just tested it and yes there is power to the relay receptacle.

 

[dave6666]

I think all that is left is the coolant sending unit or the PCM itself.

Does the '96 RT/10 have the Gen 1 or 2 powertrain? Me memory thinks Gen 1. That would mean the sending unit is different than the one I am familiar with on my Gen 2. In either case, the Gen 2 sending unit is one piece but has 2 circuits; one for the gauge and one for the PCM. If the gauge is working but the fan does not come on it could still be the sending unit at least in my case.

You did say you replaced the relays right? With new?

 

[nkbrkr2]

I am a gen 1.5. I have a engine coolant temp sensor at the back of the motor near the thermostat. Is that what you are talking about? My service manual states that it sends signal to pcm to run fan when hot and also cuts AC when too hot?? It just looks like a connector in the manual, unless what it plugs into has to be taken out of the engine itself and replaced. Is there anyway to check this??

 

[dave6666]

Having never seen one nor do I have the service manual for that year... But yes there should be a wire connector going to a sending unit that threads into a coolant path somewhere. From the correct pin, it should have a resistance to ground; the sending unit case or shell. I do not know what that resistance value would be. But if you check the correct pin to ground and it is either open circuit or a direct short, I would say troubleshooting session is over.

 

[nkbrkr2]

so I tore off the front cowl and got to the coolant temp sending unit and pulled the plug off. Now is it I jumper both connectors or send one connector to ground to get the fan to turn on??

 

[dave6666]

so I tore off the front cowl and got to the coolant temp sending unit and pulled the plug off. Now is it I jumper both connectors or send one connector to ground to get the fan to turn on??

I have not a wiring diagram on that year car so I'm a little limited in response now. I would find the terminal on the sending unit that is the resistive element and check the resistance to the sending unit's metal case; ground.

 

[nkbrkr2]

Is there a way to reset the pcm??

 

[nkbrkr2]

What do you think.... sean roe fan relay??? probably better anyway! I saw that you have one how do you like it?

 

[dave6666]

Is there a way to reset the pcm??

What do you think.... sean roe fan relay??? probably better anyway! I saw that you have one how do you like it?

I think you reset the PCM on a Gen 1 the same as a Gen 2. Remove the + battery cable and short against the chassis is the recommended method. Then you have to set WOT after reconnecting the cable. Turn the key to on and depress the gas pedal 5 fully times and release, then turn the key off and then start the car as normal.

I have the original Roe fan kit which is only an after run for heat soak management. I also have the upgrade kit which I have not installed yet that piggybacks the PCM fan controls for operation during engine run. I have not installed that upgrade kit yet.

What did you discover about your sending unit, like checking the resistance of it?

 

[nkbrkr2]

I was not able to check the resistance of the sending unit but I was able to get the plug off and tried to connect both connectors and grounding out both connectors seperately with no results except for a burnt hand! I did jumper the radiator on relay so that the fan ran all the time and noticed that it would turn the high setting on when it got really hot so the sending unit must be doing its job to tell the pcm to turn on the high setting. I have given up on it and just ordered the ROE fan relay as it will cost less than going in to have a diagnosis for it anyway. Besides I like that it will turn on sooner and help with heatsoak after the car has been turned off. I REALLY appreciate all of your help and time with this problem!!!