ABA I4 wiring confusion, "HELP"

[Vanagon Nut]

[dkoesyncro]

I went to a trusted mechanic and friend today and he helped out a bunch, It was as simple as looking at the bentley wiring diagrams for the Mk3. I now need that to finish my wiring. I had been following the schematic that Neil had posted a link to but it doesn't show the relationship w/ the starter.

How did you get your RPM signal from the coil box?

[Vanagon Nut]

Dillon: you're welcome. Fun eh? re: my comment on gauge of 15 wire from ign. switch. On my '81, the OEM wire to air cooled engine ign. coil is much smaller than same wire under OBD1 ABA. The Jetta coil may draw more current than the air cooled, but, since this Jetta 15 wire also powers (part of?) the Jetta ECU, this may be why an OBD1 ABA has a larger gauge wire. Your '86 coil wire may be sufficient. I don't know. I ended up installing a short piece of larger wire, with appropriate locking type terminal, in the ign. sw. socket. I then soldered a new larger gauge wire to that. I don't have the correct tool for (barrel?) type terminals.

vanagonjr:

Searching with google, I now recall that this relay is likely mounted in it's own holder on the top row of fuse panel. In fact, yes. I mounted this "module" and OEM holder in my relay box. I bought mine new. It was relatively pricey. $40+ Cdn?

IIRC, the HO2S relay is labelled 373. If you search this relay number, you'll see it's used in other applications. I have to wonder just how complex it really is. (to justify price?). Below shows what I think is a resistor in a generic relay. I've seen this in several different VW and generic relays. AFAIK, this part suppresses voltage spikes that may come back through the coil side of relay when engine shut down. The HO2S "module" may be as simple as that, or more complex, but since it appears VW used it in other applications (eg SAI system in OBD2), I do wonder.

Neil.

Iside my relay box. You can just see the black OEM Jetta HO2S relay holder.

Inside a relay I had lying around.

_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[vanagonjr]

[dkoesyncro]

I am obd1 in an 86' wsrbxr. I used that schematic to weed out and interface the wires needed as well as some info from A2resource. I will look into it some more after work today.
Thank you Neil!

Dillon

[Vanagon Nut]

My A3 Bentley is in my Vanagon so am going from memory. I installed an ABA Motronic into an air cooled Vanagon. It looks like you're interfacing the ABA Motronic to WBX wiring?

Are you running OBD1 or 2? What year Vanagon?

This is how I set up my OBD1 in my formerly air cooled '81:

power from ignition switch 15 goes through a larger than 1981 OEM wire (which I installed), to ABA ECU and coil. Once engine starts, (and while cranking engine?) the ECU supplies ground to engergize the "Power supply" relay which carries power to ECU, injectors, etc. When (this other section of?) ECU is energized, it supplies ground to fuel pump and HO2S relays. These relays share a fused supply from the 30 buss (battery +).

There is a wire from Battery + to ECU. This constant power enables ECU to retain it's adaptive settings but is not needed to start the engine (see below). The HO2S is also not needed to start the engine.

As does the Vanagon Bentley, the A3 Bentley has a set of tables that show you which ECU wire should show what. eg. ECU pin __ : ground. Pin ___ B+ etc. This is a very useful table. After running my engine thousands and thousands of miles (and enduring a wandering idle restarting engine warm and an intermittent MIL that I could not pin down) I re-ran the tests from this table and discovered a missing "sensor ground" and B+ to ECU 54 (IIRC) Fixing these seems to have solved the problems. Anyhow, I digress.

This page has useful info for OBD1 ABA:

http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/techset/

and a much easier to read wiring diagram.

If no cruise control, OBD1 should run fine w/o a VSS signal. This may also be true of OBD2.


Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[dkoesyncro]

So everything seemed to be going as smooth as silk, until it came time to interface the whole starter/fuel pump/Power supply relays. Actually that even went smooth its now a matter of working in concert that's stumping me. I could just be burnt out at looking at multi colored spaghetti.

This is whats happening

What you see is Fuel pump relay (on top)
Power supply/ECM relay (middle)
Heated O2 sensor relay (bottom unrelated to issue)

and this is the start wire from the forward controls/ignition switch.

I currently have the starter wire leaving the J box to terminal 50 on the starter. How do I get the power from the ignition switch/forward controls into the mix?
I should have taken better care and notes