One for the nerds - retardation relay?

[Simon Baxter]

What on earth is a retardation relay?
Never seen one, never had to fix one, can't find any info on them but they were however fitted in 1988 to T3 Diesels in relay socket 4 in the fusebox/central electrics.
There is another retardation relay fitted under the back seat of a carat for the lights on the step but I have no idea what the other one is.
Someone ordered one today and Michael asked me what it was and I didn't have an answer for him!
I can see from a wiring diagram for the fuse box that it appears to have a ignition live, an earth and an engine speed signal and that's it.

Any ideas?

[ELVIS]

Ask Hutch maybe Simon?

I know he has a couple, one on his pace maker and one in his head

[dave friday]

Does the van have aircon....if so it could operate the compressor clutch.

[Aidan]

what part number ?

[max and caddy]

Never heard of it...nothing in the wiring books I have...

[itchyfeet]

what part number ?

251919082

Switches something off when revs get too low or to high I suppose

[pionte]

I have never found the definitive answer but, I did once read that a retard relay works by applying a time controlled reduced starting voltage ... usually on Ac pumps but I think that VW used them for fuel pumps too. .... as I say not ever found the full answer.

[syncropaddy]

Is the retardation relay for the aircon not mounted in the n/s/r C post. Don't think its for fuel pumps on a diesel!

[pionte]

IDon't think its for fuel pumps on a diesel!

nope, it was on a VR6 Golf that I came accross it .

[Dutchdude]

Out of Curiosity I tried to look this up. I have the original VW folder with ALL electrical diagrams from 1979-1991. I checked the relay positions and diagrams for 1988 and can't find anything. Position no.4 on the relay board is unused, on petrol as well as on diesel. Do you have a vw part number for the relay or the two digit number on top of the relay?

The only thing I can think of is the GALA relay (Geschwindigkeits Abhangige Lautprecher Anlage) or as it translates to the speed dependant stereo volume. This uses a speed sensor in the speedometer. As the speed of the car increases, the volume of your stereo goes up automatically. It is basically an impulse doubler ( I tried to use it for the speed signal for a VDO cruise control, but used the hall sensor of a Golf mark II instead). This relay is not in position 4 on the relay board however, but on top of the relay box, above the fuses in an extra plastic mounting that clips in.

[Simon Baxter]

retard.PNG

[syncroandy]

Just seen this. In the T3 wiring diagrams, relay position 4 is shown wired like this:

Relay pin CE1 connector ref.
1 -------> Connects to eng speed signal (Alternator W) inside relay plate
2 -------> A27
3 -------> A3
4 -------> Connects to term 15 (Ignition) inside relay plate
5 -------> D3, B18
6 -------> Connects to term 31 (Earth) inside relay plate
7 -------> D8

A2 resource CE1 page suggests these pins sometimes connect to a thing they call an 'Upshift relay';

A27 -> Upshift relay pin 2
A3 -> Upshift relay pin 3
B18 -> Upshift relay pin 5, Upshift solenoid shut-off
D3 -> Upshift relay pin 5, Transmission Upshift switch
D8 -> Upshift relay pin 7, Upshift switch, vacuum (Throttle and idle switches, diesel)

Golf part number for the upshift relay is 171 919 091 (marked with a '5'). I think it puts a lamp on at a predetermined engine revs to tell the driver to shift up a gear.

A very quick search didn't suggest this option was ever fitted as standard to the T3, so the fact there's a T3 part number is puzzling.

E D I T: PS. That Golf p/n may be for petrol or diesel, I haven't checked.

[Simon Baxter]

Cheers Andy.
I'll have a look at the relay when it turn up and see if the terminals give any more clues.
Customer seems to think their van won't run without out it?

[syncroandy]

Customer seems to think their van won't run without out it?