My 350SDL has exhibited odd glowplug behaviour since I bought it about a month ago. The glowplug light will never come on when it should, but it always comes on after the car has been running for a few minutes, stays on for ~20 seconds, then goes out. I tested the glowplugs and found at least one that is certainly bad, so I assume this is causing the issue with the light, and I will just replace the glowplugs before it gets colder.

Now, however, I am wondering if this is somehow related to an intermittent no-crank problem I've been having increasingly often lately. Sometimes, I can go out and turn the key and nothing happens. The car "knows" the key is being turned- the accessories come on- but there's absolutely no clicking or cranking of the starter. The first time this happened, it was morning so I just drove a different car to work. But when I came home, the car started up just fine. It happened again a few days later- I returned to the car 5 minutes after my first attempt and it started just fine.

What could this be? Ignition switch? Starter solenoid? Starter itself? I'm wondering how to test these items or if there is another place I should be looking.

Also, last time it wouldn't crank, I moved the car in and out of Park several times, trying to determine if the ignition interlock was the trouble. But it didn't help.

If your Car is has an Automatic Transmissions the typical no cranking issues is caused by the Neutral Safety Switch and or the Shifter Bushings.

If it won't crank in Park but will crank in Neutral (or somethimes it will crank after you jiggle the Shifter around) there is a good case for an issue with the Neutral Safety Switch or the Shifter Bushings.

It could also be the Ignition Switch and that could be part of the issue with the Glow Plugs.

If your Glow Plug Relay as a Strip Fuse check that for Cracks or loose hold down Screws.

I had a crack in my Strip Fuse and got intermittent Glow Plug operation; don't remember what the GP Light did.

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84 300D, 82 Volvo 244Gl Diesel