I had a no restart condition after a brief stop. It started with a jump. I got it home and determined that the charging system wasn't. The alternator light didn't come on. I vaguely remembered a thread where it said that if the alternator light burned out, the charging system wouldn't work. So I pulled the cluster, and found that the alternator light isn't there. Just a hole in the printed circuit board on the back of the cluster. I'd post a picture but my phone doesn't seem to want to talk to the internet right now. I looked for the missing bulb, and what I'm guessing should be a socket, but didn't find it.

So, apparently I need a bulb and a socket. I think I found a PN for the bulb on Pelican, but I had no luck with the socket. Anybody know the PN for that or where to find one?

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Are you sure the bulb/socket isn't in the wrong cluster port?

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1981 240D 4sp manual. Ivory White.

I don't think so. It seems to be larger than the others. Also, it worked as intended until yesterday. I'm guessing it's either stuck somewhere in the dash or made it to the floor of the car and ended up getting kicked to the ground.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I've got probable part numbers of ECHLS6501 for the socket and ATM N177522 for the bulb. Both from NAPA. We'll see.

My project Jaguar has been down since Thanksgiving, and I just rode my motorcycle home from work in 20-some degree weather, so I'm in a bit of a hurry to get the Benz going again.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I’m really not following your post here…

“ it worked as intended until yesterday“ huh?

And then what happened? The socket disappeared?
Did you rip something out when you were pulling the cluster?
And if so, what’s left? You should at least have a wire.

If the bulb burns out, the alternator will bootstrap itself after a certain RPM.
If you simply don’t have a bulb or especially socket you would’ve been having problems for a very long time.

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1981 240D 4sp manual. Ivory White.

Light came on with the key and went out after starting and a blip of the accelerator. Then on Tuesday, that stopped happening, and I needed a jump start after stopping at a convenience store.

Yes.

I thought of that. I searched every place it could have gone and still stayed in the car. My guess is that it fell out while driving, landed on my lap or my shoe, and wound up on the ground somewhere. I know it sounds unlikely, but that seems to be what happened. There isn't a wire. This socket goes into the back of the printed circuit board and connects electrically with the board.

I ran it to the dots in 1st, 2nd, and 3rd gears getting on the freeway on the way home from Reno. That wasn't enough to excite the alternator into charging.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

The bulb sockets that are used for instrument panel illumination in both W123s and W126s are the same size as the one used for the charging light, and may be used as a substitute.
The bulbs used for illumination are about 4.5W, vs. the usual 3W bulb for the charging light. Either will work; the 4.5 will simply be a bit brighter until the output voltage rises to system voltage and the light goes out.

I got bulb and socket from Pick N Pull yesterday. I got the cluster back in and tried it. No charge indicator light or brake wear indicator. Both bulbs ohmed good. The book doesn't show the alternator charging system as a fused circuit. Is that right?

I pulled the pcb and traced the circuit. It looks like I should have bulb resistance (5 ohm) between pins 6 and 7, and I do. I checked the connector with the key on and didn't get voltage at 6 or 7.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Update:

I think I just wasn't getting good contact with that meter. I switched to a different one with a different set of leads. In addition to checking all the fuses, I took the PCB and plugged it back into the round connector. Still no charge indicator light, but I verified battery voltage at the bulb. Then I verified I was getting battery voltage all the way to the blue wire on the connector at the alternator. I checked resistance from the alternator cover to the negative battery terminal and all I got was the resistance of the leads. I'm thinking at this point the alternator is bad.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Maybe time for new brushes / regulator.....

Beware of non BOSCH or HELLA branded regulators ! .

You can solder in new brushes for $5 or so if you care.....

Get a spare regulator / brush holder from any of myriad German / Swedish junkers and carry a spare in the trunk ~ takes a few minutes to change with the passenger side wheels up on a curbstone...

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Any regulator will do for now till you can get a good branded one . I have had a chepo one in my W124 for 4 years now .But i do have a bosch in the boot just in case .

I went ahead and stuck in a new alternator, battery, and alternator belts. Batt light goes on with the key and goes of instantly when the engine is started. However, the glow plug light was awfully dim and I'm getting 12.3V at the battery at idle. The brake wear indicator light is still not coming on. Now what? Ground issues?

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Cleaned up the battery terminals and the negative cable to chassis connections. They were in "How was this even running?" condition. Brake wear indicator light comes on and goes off as it should now. Voltage at idle is still low, but I think that's because:

The glow plugs are stuck on.

Is there a quick way to enable and disable the plugs? I need to use the car all weekend and I don't have a spare glow plug relay to put in. Also, where is the glow plug relay?

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

It's on the forward curve of the left inside fender well .

You can take it apart and ever so gently & carefully clean and burnish the contact points.....

I've never had one I couldn't fix yet, they're $pendy new but plentiful & cheap in junkyards .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

If the glow plug relay is working, it will actuate when you turn the key to "run". After 20 sec, you should hear it click off. You can hear that in the cabin. 20 sec is a long time, so use a stopwatch to verify. The GP lamp going out is different. That also comes from the GP relay, but is just an estimate of when you can start cranking, dep on ambient temperature, assuming the engine has excellent compression, and all glow plugs are working correctly.

If more than 2 are burned out, that lamp will not light, as a warning. You can verify output voltage w/ a voltmeter tip on the end of a glow-plug (all are wired in parallel). To verify glowplugs, pull the 5-pin connector at the bottom of the GP relay, and measure resistance from each pin to ground. Should read <1 ohm (after subtracting DMM leads shorted together). If open circuit, that glowplug is bad. The connector has numbers to tell you which one.

On cold mornings, and with an older engine, many run 1 GP cycle, then start a second and crank. Don't keep cranking after 20 sec since the GP relay will then be off. Turn the key all the way back off and to run again, to start another GP cycle. If really cold, the engine may start but start running rougher after 20 sec when the relay turns off. I sometimes turn off the engine and go again to get another GP cycle so it runs smoother.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans