Chrysler Repair: 3.5L overheating/fan only on for 1 minute: 94 LH, chrysler concorde, coolant temp

Question
Hi.
I have 94 chrysler concorde with 3.5L and 180k mi on it. Last summer the engine started overheating in even moderately hot weather, especially in city traffic. Water pump is new. Radiator fan does come on, but goes off after a minute. Help!

Sincerely, Denis

Answer
Hi Denis,
I would begin at the fan plug and check whether both fans will run beyond one minute. The black wire is to be grounded to the battery (-) post, and then jump 12v from the (+) post to the center wire (tan) which operates the low speed fan, and to outside wire (yellow) which operates the high speed fan. If the fans work that way, then it either has to be the fan relay(s) or the control of those relays by the engine control computer. Before getting into the relays, I would check the engine computer for fault codes using the ignition key: "on-off-on-off-on and leave on", doing this in 5 seconds or less. Then watch the check engine light which remains "on" to begin to flash, pause, flash, etc. Count the number of flashes before each pause, then repeat to verify the counts. Group the numbers in pairs in order of readout to form two-digit numbers that are the fault codes. Code 55 is always last: it means end of readout. If you get a 22 that would suggest the engine coolant temp sensor is faulty, if you get a code 35 that would suggest something is wrong with the fan relay circuits. It may even be something as simple as a fan power supply fuse (fuse D, 20 Amp in the power distribution center under the hood) which has a crack in its wire and so it opens when it is called on for current, and then closes as it cools down; so look closely at the fuse. With a voltmeter you should be able to investigate how far the voltage from that fuse is going and this determine where the system is breaking down.
So try some of the tests and let me know what you find out and we can take it from there.
Roland