When the car is cold and the iginition is turned on the glow plug light doesn't come on. From reading some past posts the solutions are leaning toward the relay and strip fuse. Can anyone tell me the location of each and what I might trouble shoot. Also when we plug in the block heater there is no problem starting. 91 300d Turbo 176K
Thanks

I would go to the Diesel Giant web site and look at his how to Pictoral on checking the Glow Plugs.
It is more ofeten a Glow Plug Problem than a Relay Problem.
If in the US Harbor Freight sells Volt/Ohm (Multimeters) for $3-$9.

Below is a pic of your Glow Plug Relay.

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84 300D, 82 Volvo 244Gl Diesel

First off, your vehicle does not have a strip fuse as part of its glow plug relay; your vehicle uses a relay with a circuit breaker integrated into it. Your vehicle also has a more advanced glow plug preheater system that extends the length of time the glow plugs are energized in relation to the engine's ambient temperature.

The failure of the glow plug dash indicator to illuminate with the key in the glow position usually is part of the system's self initiated diagnostic procedure. The failure to light up under this condition means that at least one glow plug is an open circuit and has failed. If the glow indicator light illuminates intermittently while driving more than one glow plug has similarly failed.

The first order of business is to verify the glow plug indicator bulb is operational, when the key is turned to position 1 the dash glow indicator bulb should illuminate along with the other “idiot” lights.

The next thing to do is to remove the glow plug relay cover and unplug the six pole glow plug wiring harness connector. Test for +12 volts at each of the relay’s five male pins when the key is moved to the glow position. You should have +12 volts at all pins for a period of time and then the voltage will shut off at the same time you will hear the relay de-energize.

Then you will need to test the five individual wiring harness/glow plug circuits. From the six pole connector plug, test each female connector for resistance, one test lead contacting the plug’s female connector and the other test lead connected to a good engine block ground. On the meter's lowest Ohms scale you should get a reading of about .5-.8 Ohms, anything significantly higher means an open circuit and anything lower a short circuit both indicating a failed plug. The five connections within the six pole connector are numbered corresponding to the glow plugs, #1 being the front cylinder plug up to #5 being the rearmost cylinder plug.

There is a remote chance that the wiring harness between the six pole connector plug and a glow plug’s individual terminal could be failed, a test of the continuity of the wiring between the glow plug individual terminals and the other end of the wiring runs at the six pole connector plug will identify any potential wiring issue.

Assuming you've identified failed glow plugs replacing the failed glow plugs or better yet the set of five is the remedy.

Thanks so much!
Where would the relay be located?

On the Forward Section of the "WheelHouse"
[Curved metal cover over the Road Wheel,that intrudes into the Engine space]
(Confusing term,especially for those of us who are Sailors)

You can also follow the wires back from the Glow Plugs to the Pre-Glow Relay.

It'll be a bit "Fiddly" to get the cover off..."Patience Wins Out"
(It's the black box laying at a 45 degree angle,@ the picture's center)

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'84 300SD sold
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