Radiator fan motor

[karin]

I 'm having an issue with the radiator fan motor on a 1986 Lebaron 2.5 convertible. I have changed the motor, relay and the coolant switch. The motor will not come on at temperature. The a/c is not charged. I have a switch setup to turn the fan on that will plug directly into the fan motor if needed but I'd like it to work as it should. Any ideas would be helpful. Thanks.

[Kwagon2]

Hi
Your Lebaron uses two electronic modules , a "Power module" under hood and a "logic" module that resides behind the passenger side kick panel . The radiator fan relay is operated by the Logic module. The logic module receives its temp input from a two terminal temp sensor located beside the thermostat inlet commonly referred to as "the water box" so you'll have to ensure that the wiring from this temp sensor as well as the temp sensor itself is good. Check all of the fusing as well . You've replaced the relay and the motor and the "coolant switch" but there are two coolant temp sensors , one for the gauge and the two terminal one for the logic module. The "gauge" sensor has a single terminal....which one did you replace?
You need to check the wiring to the fan motor from the relay and the voltages at the relay .
Get someone who has some electrical/electronic diagnostic experience to help you as you'll need to do some meter checks .
You should also have a fault code , to retrieve the codes cycle the ignition switch three times leaving it the "on" position on the third cycle , counting the flashes will give you the codes....you may have a code 35 , code 22 and perhaps a code 17.
Please post back how you do... I'm sorry but I tried to post a wiring diagram but the site won't let me this time...dunno why.

[karin]

Thanks you so much for your response. Yes both temp sensors were replaced. Checked the grounds and all fuses are ok. The relay was from NAPA. I got a wiring diagram and I see the logic module and a thing called a wide open throttle cut out switch that ties into the fan relay and the logic module. C 25 and C 2. What do you think? This weekend I'll try the codes. Thanks again.

[Kwagon2]

Hi
The wide open throttle function operates through a separate relay located just ahead of the fan relay on the fender shield, its primary function is to shut off the A/C compressor & cooling fan on WOT. The C2 circuit also has the compressor thermal switch and the low pressure cutoff switch in it, with your A/C charge low your compressor is blocked from operation and that essentially kills the whole C2 circuit including the feed over to the fan relay. I personally would discount the A/C circuit in your diagnosis of basic cooling fan operation. Just my thoughts.....

[karin]

Thanks again. I'll try the codes this weekend and see where we go. As for the wiring nothing seems obviously bad or damaged. The car has 72 000 miles. What do think the chances are the module is bad?

[karin]

Hi again. Has a sec to check the flashes of the power loss light by turning the key 3 times then on..... they go like this.. 1,2,2,4,5,1,5,5. The power loss light does not come on when it's running.

[Kwagon2]

Hi
I should have mentioned that there is a longer delay between each second digit but seeing as how the codes are all two digit codes it doesn't matter ...so what you have is the following: Code 12 , "Memory standby power recently lost" just means that the power to the module was disconnected , generally done to clear codes in order to release a limp mode status temporarily.
Code 24: Thottle position sensor (TPS) signal is out of range and the Logic module has reverted to the MAP sensor to determine throttle position....this should result in the power loss light being turned on and the Logic module will enter a "limp mode" status.
Code 51:Oxygen sensor output indicates engine running lean too long , indicating a weak or failed oxygen sensor, will sometimes result in limp mode being initiated where the logic module will set the engine to run rich.
Code 55: Simply "End of message"
So...nothing to indicate that the logic module has picked up on an engine overtemp indicating a failed fan circuit , there is a very good chance that the logic module "switching portion ", (it is a current sinking circuit that initiates the fan relay ) has gone defective while the sensing portion is still functioning , this would require a replacement module to remedy , and if the code 24 is valid and you have no "Power loss" light on would indicate that the module is not fully reporting also indicating a malfunctioning module.... Thats my take on the situation...

[karin]

I could never find the information you're giving me! Excited seeing this going forward. Ok... the o2 sensor and the map sensor are new. The TPS is located where? I'm guessing either around the crankshaft or the throttle body. And last question is the module made for each year and model? Thank you!

[Kwagon2]

Hi
I'm glad the info is helping , most of what I'm telling you is found in the factory service manual and a bit from Chrysler's Master Tech literature issued in the 80's so its not secret stuff (However , I do have 40 years experience with Chrysler prods) .
So...the TPS is located directly on the throttle body on the opposite side of the actual throttle cable lever etc.
The logic module is part number specific for the engine & emission level (Calif or 49 state Federal/Canada) , the part number will be stamped on the module.

[karin]

Is the logic module available or does mine need to be rebuilt?