Pre-Glow Wiring - Confused - Page 2 - PeachParts Mercedes-Benz Forum

BIGRED · #16 11-28-2007, 01:28 AM

LOL... well still stuck

Guess I am back where I started.

Toomany.. thanks for trying.

I am going to have to find a few cars to study in person..it would seem. There are a number of different systems on these.

toomany MBZ · #17 11-28-2007, 01:33 AM

Sorry I couldn't help, do you have a Cali car? Euro? I'll be in the bone yard tomorrow, I'll have a look.

raslaje · #18 11-28-2007, 01:40 AM

Operation of Pre-Glow System

15-705.pdf - 0.98MB

Here's a pdf file I uploaded to a free hosting site. I couldn't upload it to the Mercedes site because it's about 1 MB (too big). Scroll through the pdf 15-705 and you'll find some schematics.

BIGRED · #19 11-28-2007, 01:51 AM

As far as I know its a Ca car.

I tried to compare it to our SD. It has yet a different wiring path than the TD. So it seems that it must be a 123 to match too. If you run across one and it helps I would appreciate it. Maybe a 116 or older 123?

My guess is that the 5th wire (green) in the last picture needs to connect to the green wire of the 2 wire pair (green and brown) which will operate the gauge. The brown must be used to transmit temp info to some device in the cabin and then it is routed back to the GP. Adding to this nonsense is an another pair that comes from the firewall and goes no where.. never has.

Thank you
Don

BIGRED · #20 11-28-2007, 01:59 AM

Quote:

Originally Posted by raslaje

Operation of Pre-Glow System

15-705.pdf - 0.98MB

Here's a pdf file I uploaded to a free hosting site. I couldn't upload it to the Mercedes site because it's about 1 MB (too big). Scroll through the pdf 15-705 and you'll find some schematics.

Thank you...I'll study it / compare it to what I have.
Don

BIGRED · #21 11-28-2007, 10:05 AM

Quote:

Originally Posted by raslaje

Operation of Pre-Glow System

15-705.pdf - 0.98MB

Here's a pdf file I uploaded to a free hosting site. I couldn't upload it to the Mercedes site because it's about 1 MB (too big). Scroll through the pdf 15-705 and you'll find some schematics.

GOT IT!

The schematic you set me is different than the one I was using. I was using the diagrams from the electrical section. The difference is that the older version preglow system diagram shows both a temp sensor for the preglow system, a temp sensor for the gauge and the wires for the later part both going into and out of the relay. Therefore 3 wires more than the newer type of relay which draws the temperature from a sensor built in (1 wire) and by not having the temp gauge wiring enter and exit it (2 wires). The wiring diagram I was using does not.

Not that it solves all the mysteries as the wiring harness I pulled with the newer relay still has an extra wire. But I think it can be sorted out.

Thanks
Don

mrmati · #22 11-28-2007, 01:26 PM

can i just say you have an amazing valve cover, did you polish it or some special order? oh and your just missing the old style metal oil cap
other then that incredible
matt

Quote:

Originally Posted by BIGRED

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).

BIGRED · #23 11-28-2007, 01:50 PM

Quote:

Originally Posted by mrmati

can i just say you have an amazing valve cover, did you polish it or some special order? oh and your just missing the old style metal oil cap
other then that incredible
matt

Thank you. I think the engine in these are special and worth the effort to look sharp. My goal is to get both the cars (eventually) to a showroom appearance, and hopefully keep them that way..

I buffed to a mirror finish the valve cover, the ALDA, the wastegate and the top of the oil filter canister I plan to continue the process over time to all the alloy parts under the hood. (if I take it out to fix it its going back buffed out).

I have the metal cap, have not polished it out yet.

Don

BIGRED · #24 12-04-2007, 11:19 AM

All hooked up and running as it should.

Big change in how this GP relay works.

No more multiple pre-glow cycles required. As the temp dropped into the upper 20's, the length of time the GP light remained on grew significantly.

Thanks to all for input.