1982 240D, Yesterday went out to the old girl and had the normal glow light and quick start scenario as it has since I have owned her.
Today, no glow light and hard long crank
Checked the strip fuse in the relay and it is fine.
What are my next steps to trace this issue down?
Thanks.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

Check your glow plugs. One or more is probably out. DieselGiant has a tutorial. You can easily test the wiring at the same time.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Thanks for the Dieselgiant tip, I will follow the tutorial and see whats up.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

On mine sometimes the light does not work even thou all the glow plugs are working I do not worry about it any more as long as it starts quickly. Usually if the light is not workng its a sign 1 or more glow plugs are out. Diesel Giant has a good write up on testing.

Well I followed the DG tutorial and after testing wiring and GP's, the last step was test the relay and voila, it tested NFG.
Do they just fail like that? It is original and 35 years is a long time but it was working fine till the other day.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

Usually before glow plugs go bad you'll notice a little white smoke on start along with a slight misfire once in awhile then they're shot a couple weeks later

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Is the fuse good in the relay? The relays have been known to stick in on position killing your battery pretty quickly.

Everything tested ok including the strip fuse except the relay which essentially read zero volts when I ran the test on it. I assume this indicates a failed relay.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

The strip fuse is a common failure item. It can get a hairline fracture in it which prevents operation. It is worth testing that you have 12V to ground on each of the screws fastening the fuse down.

The glow plug relay can take a dump on you. The points do wear out with time, however it is more likely that the capacitors on the circuit card have failed and it simply never energizes the relay. Even if the relay isn't operating due to worn points, the light should still operate if the control electronics are good.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

There is 12.5 volts at both ends of the fuse and the light is not operating.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

Is 12 volts coming into relay if they are then yes capacitators might be bad a cheap fix if you know how there is a write up on this forum as to how.

I'm not sure how similar the 61x glow plug relay is to the 60x glow plug relay, but here's my thread from earlier this year when my glow plug relay 'died'.

http://www.peachparts.com/shopforum/diesel-discussion/383193-glow-plug-relay-troubleshooting.html

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I will pull the old relay apart for a look see and while I am somewhat handy, I went ahead and ordered a new relay. Worst case is I will have a spare.
Thanks for all the great feedback.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

I'd suggest upgrading to a long glow relay. It keeps the plugs on about 3 mins after u start it. Pretty handy sometimes, especially if u got the cold start sputters...

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New relay installed, the GP light illuminates and the old girl fires up with a quick crank.
Thanks for the help.

__________________
1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily