- My 93 W124 OM602 turbo glow plug system isn't coming on.
- All 5 glow plugs tested OK
- I bypassed the controller by running a lead from the battery + directly to the glow plugs for a few seconds via the 5 pin connector and the motor started right up.

Looks like controller is on the fritz but want to rule out wiring/power to the unit. Anybody have a diagram? maybe a fuse blew? just want to make sure its the controller before ordering a new one. (from Pelican Parts of course!)

First things first, make sure your strip fuse is intact. It could have a hairline crack under one of the screws thus blocking the current flow under load. It could measure 12 V just fine without the glow plugs engaged but once the current hits it can open up the gap.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

should have mentioned it, first thing i checked.

ISSUE RESOLVED.
Turns out the nut holding the red power lead to the unit had come a bit loose. There was enough arcing across the gap to slightly melt the plastic which eventually served as an insulator denying the unit of power. I cleaned it thoroughly and bingo... perfect glow again.

I thought by early 90s MB had switched from strip fuse to circuit breaker....I don't think I see a fuse on my 91.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

not sure what came on this car from the factory as the unit on it now is a HUCO (Hitachi I believe)