Radiator fan not coming on, car overheating

JERRY ESTBY

MEMBER
2002 KIA OPTIMA
2.7L
6 CYL
FWD
AUTOMATIC
130,000 MILES

Car has three TDCs. P1529, P0500, and P0501. Coolant fan is not coming on. I replaced the ECT. Fan is still not coming on. I can make the fan run by tapping into the ground wire from the four pin fan plug that goes to the radiator fan (red, black, white, and blue or green wires) and putting it to the negative battery terminal. Is this a ground issue or is the VSS bad and telling the computer no fan is needed because it believes the car is in open loop? The ABS mil is illuminated also. Is this a separate issue or is the wheel sensor on this car acting as a speed sensor?

3 Replies

KHLOW2008

MECHANIC
41,814 POSTS

P0050 = a fault with the left front O2 sensor. Heater circuit often the O2 sensor is bad.
P0500 = Vehicle speed sensor malfunction.
P1529 = Transaxle Control Module request for Malfunction Indicator Light on. The is a fault within the transmission control system and you need to retrieve trouble codes for it.

The radiator fan is not linked to the speed sensor system. The cooling fan control system uses the engine control module tot activate a relay to ground the fan. Check the fan relays. The white wire is the main ground.

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Sunday, March 5th, 2017 AT 2:15 AM

JERRY ESTBY

MEMBER
2 POSTS

Thank you, I'll get to checking on that later today. There was a typo. It was DTC po501, not PO50. The car was driven to put gas in and won't start. Had car towed home. It will crank but won't start. Used starting fluid and it briefly started but sounded like the timing is off. There are no codes to retrieve. HELP.

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Monday, March 6th, 2017 AT 9:19 AM

KEN L

MASTER CERTIFIED MECHANIC
47,536 POSTS

Hey Jerry,

You have a couple cooling fan relays that could be bad. Here is a wiring diagram and a guide to help you get the problem fixed.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please run this test and get back to us so we can continue helping you.

Best, Ken

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