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Preignition dash light not coming on

Posted: Thu Dec 28, 2023 12:01 am
by TemescalTom
Happy Holidays All, I haven't started my coach in several years. Went to start and engine turns over but there's no light for the preignition heater. It didn't start even after several tries and the pre-ingnition light never illuminated. I checked wiring around the starter, all around engine area and no evidence of wires damaged or chewed through by critters. Any idea of where to look next? Everything else in startup sequence appears operational. Thanks in advance and Happy New Year! Tom
1997 Safari Ivory 3730, 3126 CAT/4060 Allison

Re: Preignition dash light not coming on

Posted: Thu Dec 28, 2023 8:17 am
by wolfe10
Have you checked for power at the intake manifold heater solenoid (top of engine) when the key is turned to the first position?

BTW, you will have the Allison 3060, not 4060 with the Caterpillar 3126.

Re: Preignition dash light not coming on

Posted: Fri Dec 29, 2023 9:42 am
by Glenn
Hi Tom,
You mentioned that "everything else in the startup sequence appears operational." Does this include the Check Engine light illuminating for 3 to 5 seconds after "Key-On"? If the Check Engine light does not illuminate when the key is switched on, the ECM isn't powered up. Without the ECM powered up, the starter will still crank but nothing else on the engine will function. Power to the ECM is controlled by a relay on the wiring harness between the batteries and the engine. I located mine attached to a frame member behind the battery tray, had to roll the tray out to find it. I've had problems with it multiple times.

Best of luck,