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Wed Nov 20, 2013 2:56 pm

I'm trying to figure which wires go to which components in the attachment. The small wire labeled (1) was unplugged preventing a startup. I reconnected it and the car started; however, I'm just not wire savvy enough to know what it (or the other wires do).

Please can anyone out there identify wires 1, 2, 3, and 4. Thanks in advance!

Peyton
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Wed Nov 20, 2013 6:14 pm

Looks like a home-made version of what Bosch sells as the WR1, low-voltage/hot-start relay kit... minus an inline fuse.

Thu Nov 21, 2013 1:47 am

I don't know if anyone could answer your query without more info:
Where do the visible wires run?

The big red wire? Does it run to the battery? Does it run out the rear of the cabin?

The purple wire, where does it go? To the wiring harness at the left side of the car?

The #1 wire does not appear to connect to the relay at all? Most relays require four wires minimum. Yours appears to only have three wires connected. Is there a fourth wire hidden behind #2?

When you turn the ignition switch to the START position does this relay "click", indicating it is working?

Are any of these wires powered (12v) all the time?

Thu Nov 21, 2013 12:45 pm

Dear AshMan40

So far I have figured that the big red wire runs from the battery to the #2 contact. #4 goes to the solenoid. The purple wire leads into the relay from the voltage regulator. I believe #1 goes from the regulator to the solenoid (or is connected to another wire leading to the solenoid). There is a green wire hidden behind #2 (I don't believe it goes to the solenoid but it originates at the voltage regulator). The black wire hidden under #3 and #4 goes to a ground. The plastic connector (#1) does not contain a fuse --- it is just a connector. I have no idea of its function.

I have hooked up a WR-1 relay to the car also---I guess this means there are now two relays! The car is starting great now but it would be nice to know the original setup. Thanks for your input.

Peyton

Thu Nov 21, 2013 12:49 pm

Dear Glutamodo

Thanks for your reply. I did install a WR-1 and, for some reason, the car is starting great now --- with two relays!

Peyton

Thu Nov 21, 2013 3:00 pm

pernest wrote: The car is starting great now but it would be nice to know the original setup.
The "original" setup from VW had no relays between the ignition switch and the starter solenoid. VW had current flowing from the battery, to the ignition switch and then all the way back to the starter solenoid. That junction you thought might have a fuse is the stock wire junction between the ignition switch and the starter solenoid. It is large because the wires used are heavy gauge.

Don't get me wrong, the hard start relay (HSR) is a good idea. It reduces the current flowing through the ignition switch (extending its life) and increases the current that reaches the starter. As a relay its function is to trigger the flow through a high current circuit using a small current circuit.

The HSR normally has four wires (the terminal numbers correspond to the above diagram that uses a common Bosch-style SPDT or SPST relay):
#30 - constant 12v battery source for large current flow. This connects to battery positive terminal.

#87 - switched normally open (NO) output. Shorted to #30 (closed) when relay is energized. Bosch relays normally handle 20A to 40A current flow from this terminal. This connects to #50 terminal on the starter solenoid.

#87a - (optional) normally closed (NC) output found on SPDT relays. Shorted to #30 when relay is at rest (not energized). This terminal is not used for HSR installations.

#85 & #86 - relay control. When one of these is grounded and the other powered by 5v to 14v the relay will energize. One of these goes to ground. The other connects to the ignition switch via #50 wire. The #50 wire should normal be a heavy gauge (around 8AWG?) red wire as it originally had to power the solenoid directly. It doesn't matter which of these two are power or ground. They are interchangeable.

Note that none of the HSR connections go to the VR. Maybe you could connect #30 to the VR B+ terminal as this comes from the battery positive terminal, but tapping current from B+ means there is potentially less current for all the other accessories. Connecting #30 to the battery terminal directly is the best.

Thu Nov 21, 2013 4:11 pm

Dear AshMan40

Thanks!

Peyton

Thu Nov 21, 2013 5:32 pm

By the way, the WR1 comes with a 15 amp fuse. VW's rated maximum allowable "pull in current" for the Bosch starter solenoid was 35 amps... and I've seen it where a 15 amp fuse simply is too small. I'd recommend a 25 amp fuse myself.

Thu Nov 21, 2013 7:49 pm

Dear glutamodo

Thanks for the advice on the fuse ---- will change to 25 amps.

Peyton

Fri Sep 29, 2023 9:31 am

You have a newer thread on this same subject, but 10 years later!

https://www.thesamba.com/vw/forum/viewtopic.php?p=10119364