I pulled my cluster to fix the odometer and planned on replacing all the bulbs. The glow plug light hasn't come on in some time but the car starts fine even on cold winter mornings so I figured it just had a burnt out bulb. I swapped the bulb but still no light? I did notice the other indicator lights have two wires going to them but the glow plug light only has one wire. It looks like it could have had two previously. i looked around in the dash but there were not any loose wires.

Anyone know how many wire this should have? or what other issues could be causing the light to not come on?

thanks,

G

A clue as the the make, model, and year of the car would be helpful.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

yup, that would deffinately help.

1987 300D - W124

The GP light has only 1 wire, IIRC. The casing is metal and is connected to chassis when plugged in. Start with the basic first: I would first measure the GP to make sure all GP are good. Remove the BIG connector at GP relay. Poke every hole in the connector and measure it against chassis for continuity. They should be 1-2 ohm. Starting fine does not mean all GP are good. If all GP are measured good then the GP light should come on. If not then it could be the GP relay or wiring ( IMO, unlikely ). Good luck.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

thanks,

i will start there.

Try jumping pins 1 to 3 on the small glow relay connector with the key in position II. That should light up the glow plug indicator. That will rule out a bad bulb or bad ground.

It's true, this is the only bulb that has 1 wire and a clip for ground. It's possible that the ground between the sections of the instrument cluster is bad. The tach/clock has to ground through a strap across the back of the speedometer to the fuel/oil/temperature section, and then on to pin 1 in the big round connector to the W1 ground point.

If the light won't work and the car starts fine, then it is possible that the glow plug light control circuit has failed. Or you have really good compression...

Try this first, open the shell of the small 4 pin connector and carefully tighten the connector pins and inspect them for corrosion. Do not sand them! They are silver plated, if corroded, use Tarn-x.

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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