Testing Starter relay switch

[Moose]

Command to start doesn't come through the ECM on Paccar. Smacking ECM won't help anything here. The best way if you can get it to act up is with a DMM while it's not cranking. You will have 12v from the CECU to the key switch going to a relay in the cab then that relay on the firewall then to the starter.

[Andre_The_Giant]

Thank you, I’ll spend some time with my multimeter this weekend, I’ll post up what I find

[Moose]

I just fought mine trying to get it figured out. I had a bad starter solenoid. It would throw the bendix out into the ring gear but not make good enough contact to energize the motor but only occasionally. Then to complicate the troubleshooting the OCP on the paccar side would take hold and I would lose all power downstream of the relay in the dash until I cycled the key. :waaaht: You want to talk about making clutch adjustments a real pain in the ass.... It took a DMM and a helper at the key switch to finally get it. A test light would work too.

New starter and Paccar offers a jumper to put in place of the relay. Now it starts, bumps, whatever the key tells it to do now.