I am trying to sort out the pre-glow wiring/relay system. I have read (to my ability) the wiring diagrams on the CD and am stuck.

On the 80's and earlier I see where there is a relay that makes use of a sensor in the block (I would guess the same as a temp sending unit). That wiring harness has a female plug that contains 7 wires, 1 for each plug, temp gauge and temp sensor.

On later diesels (mid 80's), there is another wiring harness that has 2 female plugs a 5 and a 2. 5 for the plugs and no diagram of the other 2. The 2 wires have the same sending unit connectors and therefore it appears that one is for a gauge and the other for temp sensing.

I can see where the gauge wire would hookup but can't see anyplace for the temp sensing to connect and or what system it would be used for.

I am going through all this to upgrade the system.. the old one kicks off to early.

Thanks for any help!!
Don

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

I believe the other plug is for the timer. When I unplugged that one and turned the key, I had no dash light come on.

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83 SD

84 CD

The original relay on our 300D was kicking off after about 10-12 seconds so I swapped it all out with a new afterglow kit. Well worth it.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

What car are you working on?

Are you working on the '80 or '83?

Also, I'd be glad to contribute what knowledge I may have, but I'm not really understanding if there is a question here. Knowing what car you were working on would help, as I'm not sure about the '80, nor do I know if it is the same as an '83, but I have an '83 and '82 and could help if I knew exactly what you're trying to figure out.

Is your system unhooked? I understand you're upgrading, but what are you upgrading? Plugs, relay, both?

I'm curious as to why you say your system kicks off too early? Are you referring to the light on the dash turning off too early, or the actual relay "clicking" off too early? Sometimes after my light turns off on the dash I go ahead and sit there for 5 more seconds just because I know my relay is still heating my glowplugs and want to make sure my car starts up as smoothly as possible with none of those "winter clanks." Knowing this would help me help you.

If your relay just isn't staying on at all then you need to replace the actual black box relay that the g.p. wires go to. The box with the two plugs and strip fuse inside it. I believe the timer is built in and it is an internal part of the relay. You can test the length the timer stays on with a multimeter too.

Post some more info so that myself or others can be a little more specific.

-J

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1974 240d "Peace, Love and Empathy" - Kurt Cobain
1982 300sd "It all depends upon the Benz!" - Me
1983 300sd
1985 500sel
1992 300se

Wire in one hand..... nothing in the other

Where do I put it?

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

I am working on a 80 TD that had a 83 turbo put into it. The GP system appears to be from the 80 vintage. The light was going out quickly and trying (cough) to explain to my wife the proper starting procedure proved ... how should I put it...ummmm lets just say she isn't mechanical inclined, reclined or unlined. Being we have a number of cars she doesn't keep track of which car has this quirk and so on. In an effort to make it easier for her..I pulled a relay and harness from a 83 car (assuming that one was original) and I am trying to wire it in.

The 80 had two wires as part of the harness that along with the 5 for the GP's plugged into the relay. Each one of those wires attached to a sending unit in the block. I assume one was for a gauge and the other a temp sensor that affected the GP glow time.

The "new" wiring harness has 2 plugs. One with 5 for the GP's and the other one 2 again for 2 sending units. There relay can't receive all the wires I think it can take 6 of the 7 5 GP's and through a splicing, one for the temp gauge (I think).

Thanks for the help!

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

Not sure of the question, but I have not tested the timer plug in any way. You may be able to, with a multimeter, put the red lead in one of the female other in male, or ground, turn key, see what you have.

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83 SD

84 CD

When you say you unplugged the timer... I have no idea where that is located and or the color wire that is.

I have the wire coming from the harness....but do not know where to put it.

__________________
1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

Ah, the timer is a plug located just aft of the GP plug in the relay. Pop open the top, you'll see it. It is the smaller of the two plugs, four prongs.

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83 SD

84 CD

Nope...not the ones. That group of wires heads towards the fuse block. The extra wires I have are coming from the harness that has the glowplug wires, in total 7.

I guess I will take some pictures today and that might help clarify things.

__________________
1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

they call it the purple or violet wire. I'm still looking for it. I have no solid purple or violet wire at the glow plug relay, just black wires with color stripes. there is a purple stripe, but I don't know if thats the one.

Picture listing and info

1. New relay on left, old on right. New has 2 sets of pins. One with 4 pins and the other with 5. Old has 2 sets of pins. One with 6 the other 7. The harness from the fuse box had a total of 5 wires in it. The harness from the GP and sending units had a total of 7 wires
2. Shows the 2 sending units in the block that hook up to the old wiring harness correctly.
3. Repeat of 2
4. Repeat of 2
5. New Relay installed with new GP wiring harness and the wiring harness coming from the fuse box, with one wire not connected. The harness from the GP and temp sensors has 2 plugs. One (attached in picture the larger one) with 5 wires and the other (not attached with 2 wires ...end not in picture but you can see the green and brown wire).

Attached Thumbnails

         

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

My relay is the one on the left, in the first pic, 5 and 4 pins. The wire bundles on mine are virgin.
The other relay is for a six cylinder?

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83 SD

84 CD

The one on the right is for a 5 cyl as well. It seems over time the method of feeding the relay temp information changed. The one on the right connected to both sending units on the block, one for the temp gauge, the other to feed temp info to the relay.

Being that you have the one on the left, does your GP harness have a total of 7 wires that branches into a 5 wire and 2 wire plug? If so, where does the 2 wire plug hook up.

It is here that I am having issue with the schematics on the MB CD's.

Thanks
Don

__________________
1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

I have only one temp sensor, between GP #2 and#3. Just a metal engine plug between #1 and #2. Just five for the GP's, not an extra two, and four for the timer, one to the sensor, don't know about the rest.

Hard to see, but the red circle is the sending unit.

Attached Thumbnails

 

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83 SD

84 CD