Customer complains of intermittent C.E.L accompanied by an intermittent battery light illumination Codes pulled: P1492 Battery temp too high

The P.C.M in this system communicates with the ambient air temperature sensor to determine the batteries temperature in its cubby on the passenger side fender compartment. Checking 2-wire sensor I found that the REF voltage received from the PCM only displayed 2.5v (unplugged as you must check with thermistors) -Note: this car has had multiple repairs including the radiator, condensor, and was in a front end collision.

Checked pin #52 at the PCM which was a Violet/Grn wire, also displayed 2.5v.

at this point, my thought was a corroded wire between the sensor and PCM, or a corroded circuit/voltage regulator inside the PCM.

Next step- cut the wire, recheck the voltage to determine PCM output, spiked up to 4.5v (.5 ref gone from battery drain)

Fix- Rerouted new wire between PCM and Ambient air temp sensor.

Hope this helps someone!

-Alex

Alexander Davis
Technician
A to Z Automotive & Repair
Villa Park, Illinois, USA