PeachParts Mercedes-Benz Forum - Afterglow and the Violet Wire

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- - Afterglow and the Violet Wire (http://www.peachparts.com/shopforum/diesel-discussion/88637-afterglow-violet-wire.html)

Quote:

Originally Posted by Astroman

I ran some lines through the firewall before and yes, it's a $@#%. Since I ended up with a switch, I didn't install a light, but it is

Take a look at this picture. It's a picture of the main harness where it goes through the firewall on a 78 240D. Same design on other models. You can pull those little plugs out and run wires through. This way you don't have to make any new holes and you also have a pre-made grommet.

Could someone post a picture of the 603 setup with a thermal switch installed and where I can get all the parts? I'd like numbers if I could since I'm no electrical engineer. I understand the switch at the thermostat housing is the one used, but I don't get what relay is being used and how it's all wired up. Yes, I read the whole thread.

You guys are great.
Thanks
David

Well, the thread originator had the temerity to go and get himself banned, so he can't respond--what a jerk. I guess I'll stand in for the jerk and try to decipher his cryptic ramblings...

He found the relay in a wrecking yard, but you can also order one from your favorite vendor. I don't have a part number, but MB uses these relays extensively, so go look in your fusebox to see which has the corresponding terminal numbers and get the part number off of that one.

The 86 terminal is wired to the temp switch on the t-stat housing.

The 85 terminal is wired to a 12v keyed source (w/inline fuse).

The 87a terminal is wired to one side of the snipped violet wire.

The 30 terminal is wired to the other side of the snipped violet wire.

The 87 terminal is not used.

He snipped the violet wire approximately 2" back from the relay, which required trimming the harness cover a bit.

This is a very effective modification. Highly recommended.

You could also do the same thing but with a time delay relay....the 30A 5 terminal relays are EVERYWHERE. Any autoparts store should have good stock of them. The time delay relay is a little harder to find...I think rat shack stocks them. They are very common. You could use a switched 12V supply and have your violet wire "hot" for a pre-determined amount of time...it is adjusted by a POT on the relay base. Just saying that there is more than one way to skin a cat. You could also have an override switch so you could have it on as long as you want...just more ideas.

Thank you both very much. I'll be sure to try and do that. I assume they were speaking of the black wire with the purple stripe? I pulled that one wire out of the plug and put electrical tape around it for now. I have one GP burned out so this should help greatly.

Thanks
David

I took the black wire with the purple stripe out of the harness and moved it to the side. I then covered it with electrical tape so I can out it back when it wamrs up outside. Really, I don't know if I notice much of a difference once the car is running. It still has the usual 603 cold starting problem of smoke and missing.

Thanks
David

If you still have one or more burned out or out of spec GPs, then this mod may not help all that much. On the cars I've played with, this mod has produced fairly dramatic differences while the relay is actually energized--the positive effects taper off from there. Do you know whether your chain stretch and IP timing are within spec? How about injectors--air cleaner--delivery valve seals/o-rings, etc.?

I have noted substantial results in the SD...all GP are working fine and dandy and the mod is as listed above using the temp sensor as a trip to prevent full glow on warmed engine starts.

Quote:

Originally Posted by Brandon314159

I have noted substantial results in the SD...all GP are working fine and dandy and the mod is as listed above using the temp sensor as a trip to prevent full glow on warmed engine starts.

Just make sure your temp sensor isn't bad before you go and do this mod. Otherwise you will be replacing glow plugs every 4 months.

Quote:

Originally Posted by Zeitgeist (Post 581426)

I posted this on the mbz.org diesel list earlier today:

As many of you are probably aware, if you snip the violet wire at the GP relay, you can get your GP's to glow for an extended period after the engine is running. This should theoretically reduce smoke, emissions, and coking issues. The problem is that snipping the wire also forces the GP's to run 'afterglow' even when the engine is warm, which will diminish the life expectancy of the plugs. Many folks have wired in a manual switch to turn off this feature, but I wanted a more 'hands-free' operation.

I installed a thermally switched relay into the GP relay's violet wire circuit. I used an NC (normally closed) relay from a Volvo 700 series fusebox. These are a 5 terminal relay, similar in look to the familiar 4 terminal NO (normally open) versions used in Euro headlite conversions and countless other little projects. These NC relays have an additional 87a terminal to which one side of the violet wire is connected, opposite the 30 common for the other side. http://www.the12volt.com/relays/relays.asp Be careful of other similar 5 terminal relays with an 87b terminal--these are just NO relays with two bridged terminals--these won't work.

I piggy-backed onto the 50 C thermal switch above the thermostat housing on my '87 300 td OM 603, which is apparently designated to assist and smooth cold shifting in the transmission.

When the relay is energized, the violet wire is snipped--afterglow enabled. In this phase, the 50 C thermo-switch has continuity with ground.

When the relay is not energized, the violet wire is bridged--afterglow is disabled. In this phase the thermo-switch has no continuity with ground.

I'll let you know how well this works in real world situations.

Well, it's that time of year again. This modification still works quite nicely, even after all these years.

Quote:

Originally Posted by H2O2 (Post 816977)

I found the relay in a wrecking yard, but you can also order one from your favorite vendor. I don't have a part number, but MB uses these relays extensively, so go look in your fusebox to see which has the corresponding terminal numbers and get the part number off of that one.

The 86 terminal is wired to the temp switch on the t-stat housing.

The 85 terminal is wired to a 12v keyed source (w/inline fuse).

The 87a terminal is wired to one side of the snipped violet wire.

The 30 terminal is wired to the other side of the snipped violet wire.

The 87 terminal is not used.
I snipped the violet wire approximately 2" back from the relay, which required trimming the harness cover a bit.

This is a very effective modification. Highly recommended.

More information...

What about the 617?

If I understand this thread, the mod was developed on a 603. Does the 617 have a similar thermal switch that can operate a relay?

Quote:

Originally Posted by Jeremy5848 (Post 1329414)

If I understand this thread, the mod was developed on a 603. Does the 617 have a similar thermal switch that can operate a relay?

It uses the same violet wire.

If you want the full factory afterglow setup on a 603, here's a link to a thread with details on how to do it, including photos, part numbers, etc. I've had this on my car for about 18 months and I love it.

http://www.***************/forum/showthread.php?t=398

The violet wire trick is free, but will reduce plug life somewhat compared to the factory afterglow setup (which varies afterglow time based on coolant temp).

:scholar:

well, after looking at my 617, it seems that there is a light gauge violet wire, which i am sure is the one we want. but there is also a black wire with a violet stripe. heavier gauge. this appears to be gloplug wire, so dont cut this one.

i noticed a few people ?? this when i first read the thread, just want to clarify this, as some people may just see that bl/v wire and not look further.....