'93 Daytona radiator fan stays on

[ntxdodge]

I have a '93 Daytona IROC RT with a radiator fan that stays on. The car starts up and the fan is off. When the engine warms up the fan come on and doesn't go off. The fan does shut off when I turn the motor off. I've change the fan relay solenoid and the fan still acts the same way. The engine tends to run cold via the temp gage on the dash.

The water coolant temp sensor is new, is there a way to check if the sensor is bad? I do not have any codes from the computer.

Any ideas on what I should look for?

Ron

[tryingbe]

Any code?

[charger R/T]

Is the A/C switch on?
Tim

[ntxdodge]

A/C switch is Off.
I'm not getting any codes.

I just replaced head gasket, car runs perfect with about 500 miles since replacing the head gasket. That is with the exception of the fan staying on.

Ron

[NAJ]

There is the possibility of air in the system and the controller thinks the engine is hotter than it is.
All relays function the same way so they are easy to check.
With the connector plugged in to the fan relay and the engine running you should have power at 2 terminals.With the fan not running the other 2 should have nothing.
When the fan cycles you will now have power at 3 terminals(1 is the power out to the fan) and the last terminal is the controller ground. Connect your test light to Batt + and probe the ground,your test lamp will light and will go out when the controller wants the fan to shut off.
If the test light goes out and the fan keeps running replace the relay.
If the light does not go out the controller is commanding the fan to run,then you have to figure out why,what is it seeing?

[phantomrt]

Which temperature sensor is new? There are two of them. One for the guage on the dash (1-wire sensor) and one for the engine computer, which is a 2-wire sensor.

Seems like a massive air pocket in there somehow. I have little experience with T-III's and how much of pain it may be to bleed their cooling systems, but that seems to be the case. When the fan is running, is the fan blowing hot air or is it cold? If it is blowing cold air, rev it up to about 2000 RPM and feel to see if the temperature of the air being blown around changes. If it does, you definitely have an air pocket in there. FYI, with air pockets in the cooling system, the temp sensors may or may not be reading accurately if at all.

Also, what is the chance this engine computer isn't modified?

[ntxdodge]

Both temp sensors are new! the gage and the water coolant temp sensor.

I did drill a 1/16 hole in the thermostat to allow air to get out. Saw this in some other Turbo Dodge TIII write ups.

If I do have air in the coolant system what is a good way to get rid of it? Before I changed the head gasket I was getting bubbles in the over flow tank. I was getting a lot of exhaust in system and it was throwing codes like crazy. I am not seeing this since I changed the head gasket. No codes or bubbles. I have run the heater to get rid of air in the coolant system. Any other suggestions?

What can I look at on the computer, that is a possibility since previous owner was into mods?

Ron

[ntxdodge]

Forgot to mention the car starts off cold with Radiator fan off. Roughly when the thermostat opens the the first time the fan usually turns on. The air temp from radiator fan is hot initially and then get cool, that is until the thermostat reopens and send new hot water into radiator. During the hot / cool / hot cycles the fan stays on.

Ron

[charger R/T]

what temp thermostat did you put in? Is the boost still controlled by the computer and if so what is it boosting too? (just trying to figure out if you computer is chipped) When I put my chipped computer in it has revised fan schedule and the car still had a 195 degree thermostat and the fan ran alot since the thermostat was hotter then the fan schedule was set for. Replacing the thermostat with a 180 changed that.
Tim

[ntxdodge]

Tim,

This is a California car, previous owner tried FWDPerformance module. Car didn't run right or pass California emissions. He ended up replacing with new Mopar stock TIII module to pass emissions. He said he left new stock TIII module in place since FWD Performance module didn't work properly.

I'm in Texas, and the car just passed our emissions test (up the tail Pipe) last week.

I'm running 195 Degree thermostat in it right now. I'm getting about 12 psi boost, so I believe it is stock module.

Is the module your talking about on passenger side kick panel? I can take a look at it, but I'd like to know what I should be looking for.

Thanks, Ron

[NAJ]

Did you determine that the problem was related to the controller keeping the fan on?
Since you have a scan tool you can look at fan control and see if the controller is commanding the fan to stay on,you can also actuate the fan with the key on/engine off to check relay operation.
If there is air in the system you will see coolant temp on the scanner rise to a certain level and not come down even with the fan running.

[ntxdodge]

I don't have scan tool, wish I did but I do have the Chrysler standby turn the ignition key 3 times and leave ignition on to count the blinking light. I did recheck codes tonight tonight and I do have codes
12 - Battery disconnected recently
53 - PCM interanl fault detected
55 - End

The PCM (Powertrain Control Module) internal fault code may be the problem. PCM is on drivers side fender near the battery per book. Not sure what to look for, any ideas?

[NAJ]

The cooling fan running is still your concern?
If so you still need to determine if the controller is commanding the fan off or the engine is running hot as I decribed earlier.
I also remember someone on this site saying that the code 53 was normal if this is a performance controller.

[ntxdodge]

I saw that but the '93 has a fuse and relay box. The relay is not separate to do a probe. I did swap out relays with no change in fan turning off. The Chrysler manual says the PCM grounds the fan relay when the coolant temp sensor reaches predetermined temp or the AC is turned on.

I'm gonna check the grounds near the PCM.
My other option is that it does have a Performance controller.

[charger R/T]

a 53 is normal with some chipped computers. It sounds like he didn't leave the stock computer in it. Why not put a 180 thermostat in it and see if the fan issue goes away. You could also pull out the computer and take the cover off and see if the one corners of the potting material has been removed to chip it. looking in the end with a light can also see where the same area
Tim