The engine protection system warning lamp circuit is a positive (+)
12-VDC (24-VDC in U.K. and Europe) supply from the vehicle keyswitch, a lamp or buzzer, and wire number 1 (engine protection output driver).
Measure the voltage between the fault lamp and ground. Turn the vehicle keyswitch ON. Touch the positive (+) multimeter probe to the buzzer or lamp terminal. Touch the negative (-) multimeter probe to the chassis ground. Measure the voltage. Repeat this check for the other terminal of the buzzer or fault lamp. The multimeter
must show battery voltage. If the proper voltage is
not present, there is a problem with the keyswitch wire, or the lamp (or buzzer) has failed. Refer to the OEM troubleshooting and repair manual for repair instructions.
Connect all components when the repair is complete.
Hello, I'm Jack, a diesel engine fan and a blogger. I write about how to fix and improve diesel engines, from cars to trucks to generators. I also review the newest models and innovations in the diesel market. If you are interested in learning more about diesel engines, check out my blog and leave your feedback.
View all posts by Jack