Tech Help needed - fans do not kick on.

[Disturbed]

So I got this race car from Ringgold in trade for my ACR.


So far, I've haven't been able to drive it (other than once to go get gas and it started to over heat).


I started to trouble shoot it and this is what I found.


1.) NO WATER.

Filled it, burbed it.

2.) Cooling fans do not turn on.

Appling power to the fan at the connector - works

Thinking the relay could be bad, I swapped them - no change.

I removed the fan relay and jumped it with a paper clip - works

Checked the temp sensor, temp gage goes to Zero - works

I cleaned and reseated all connections.

50 amp fuse is good.

I get no codes.

You can see when the T-stat opens and the temp will drop until all the water is warm. Then the temp will rise until I shut the car down at about 225 deg.



Here is what I'm thinking. It has to something at the PCM. I was looking for a pinout but I can't find anything to show me what wires are used for the fan. It looks like they had a VEC or something hooked up but it has been removed.

Below is the only pin out I can find of the ECU but it doesn't help 1996–2002 Dodge Viper ECU Diagram

 

[99 R/T 10]

Until you can figure it out, might be a good idea to put the fan on a manual switch. It's a race car anyway, should already have one

 

[likecolor]

check the waterpump,sounds like no circulation.

 

[Disturbed]

Until you can figure it out, might be a good idea to put the fan on a manual switch. It's a race car anyway, should already have one

I was thinking about doing that as a temp fix....but not really how I like to do things.


It's not the water pump. as you can see because the coolant temp will drop when the T-stat opens (at least until all the water gets heated up).

 

[Disturbed]

Thanks Joe for the scan of the manual. You rock. I don't care what they say about you.

 

[Chuck 98 RT/10]

Might be operated with a toggle switch.

 

[Steve-Indy]

I would also bet that there is a toggle switch already installed...or, at least an OEM switch that has been converted into a fan on/off switch.

 

[Disturbed]

Might be operated with a toggle switch.

The only toggle switch is for the Accu-sump pre-oiler.

 

[Big Mac]

Does anyone have a diagram for a DIY switch?

 

[Tom F&L GoR]

a few ideas.

Make sure the cooling system is truly full.

There are three temp sensors (at least on Gen 1; one for idiot light, one for gauge, one for PCM.) If the liquid is not hitting the PCM sensor, it won't turn the fan on. checking the gauge sensors only checks the gauge.

Locate the PCM temp sensor. Either disconnect it or ground it, whatever makes it think it is hot, and see if the fans come on. Meanwhile, any smart people know if the PCM gets fooled like this or does it "know" you're faking it out?

 

[Disturbed]

What I found out is on a Gen II you have 1 temp sensor for the PCM, gauge and light. Because the gauge is working, I know the sensor is good. But is the connection at the PCM good, I don't know until I have time to mess with it this weekend.

 

[ollikoi]

Engine coolant temperature sensor includes three different sensor. One for gauge, one for PCM and one switch for warning light. Four wires, one is ground.
I think problem is in sensor.

PS.Grey connector in PCM. Pin 2 is Radiator fan and pin 21 is High speed radiator fan.

 

[ollikoi]

"You removed the fan relay and jumped it with a paper clip - works"

OK Remove it again and chek relay pins 94 and 96.

94 must have 12V all the time and 96 gets ground from PCM if engine needs cooling.

 

[Disturbed]

Thanks to MTGTS for swinging buy and letting be use a few parts off his car for testing.


While we don't know the exact fix....it seems to work now. It started to work after we re-seated the PCM. I did that once before but it didn't work. We ohm'd out the wires and they are fine, I'm betting it's a intermitted PCM or wire.


Looks I like I need to place a call to Roe to get that T-stat on order.

One thing is for sure, this car does run warmer than my ACR did. My ACR never hit 210, it stayed at 190. I'm betting it was due to the AEM turning the fans on sooner and the fact I had a 180 degree thermostat.

 

[dave6666]

One thing is for sure, this car does run warmer than my ACR did. My ACR never hit 210, it stayed at 190. I'm betting it was due to the AEM turning the fans on sooner and the fact I had a 180 degree thermostat.

I drove another 2001 GTS recently. Sapphire for those that might wonder... Anyway, that car the cooling system per the gauge ran 10 degrees cooler than my 2001 GTS does. Even the point the fan kicks on per the gauge was 10 degrees lower. Neither car has a modified fan control.

Moral of story IMO - The OE gauges are not that accurate. More than likely the cars ran at the same temperature. Maybe yours do too.

 

[MTGTS]

I drove another 2001 GTS recently. Sapphire for those that might wonder... Anyway, that car the cooling system per the gauge ran 10 degrees cooler than my 2001 GTS does. Even the point the fan kicks on per the gauge was 10 degrees lower. Neither car has a modified fan control.

Moral of story IMO - The OE gauges are not that accurate. More than likely the cars ran at the same temperature. Maybe yours do too.

Yeah, we put his PCM in my car and the fans didn't come in till about 22-230. We were about to turn off the car and chalk up the whole thing to the PCM. Then the fan came on and we were

 

[Tom F&L GoR]

What I found out is on a Gen II you have 1 temp sensor for the PCM, gauge and light. Because the gauge is working, I know the sensor is good. But is the connection at the PCM good, I don't know until I have time to mess with it this weekend.

I looked in a '99 manual and my '94 manual. What ollikoi says is correct; the three sensors of the Gen 1 are now incorporated into one unit, but the Gen 2 wiring diagram still shows the three functions separately (inside the unit.) Something to keep in mind, since a good gauge reading isn't the diagnostic tool you were hoping.