The fans will not come on, but work when straight wired to the battery

1999 PLYMOUTH VOYAGER

STPMTCH44

MEMBER
1 POST

The fans will not come on, but work when straight wired to the battery. We realized this after purchasing new fans and had the same result. We are not certain which is the fuse to check it. I have to run it straight wired until payday. What else can we check? I have a friend that will scan the system tomorrow. Will that tell us for certain what it is as the engine light is on? I will gladly donate when I get more money.

Aug 2, 2010 at 7:09 PM

SQM

✓ASE Certified Mechanic
6,383 POSTS

Hello,

An inoperative cooling fan can be due to a faulty relay, bad wiring, malfunctioning coolant sensor or a bad fan motor.

First check the relay. On this vehicle it is called the solid-state fan relay or SSFR.
It is located on the left front inner frame just behind the radiator (see diagram below)

Here is a guide on how to test relays:

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

If the relay is good, then the issue could be bad wiring of a faulty coolant temperature sensor.
Malfunctioning coolant temperature sensor will be unable to send the correct data to the ECM to turn on the fan.

https://www.2carpros.com/articles/how-a-coolant-temperature-sensor-works

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.

Images (Click to enlarge)

Professional Diagram for 2CarPros Members
Click here to log in and view diagram.

Dec 20, 2021 at 8:13 AM