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T3 wiring help

Discussion in 'T3 & T4 Tech Help Clinic' started by Andy., Aug 5, 2015.

  1. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Hi all,
    I have pulled some of the wiring out of the T3 ('89 caravelle). I have a Bentley manual but having trouble deciphering how it all works!
    I am looking to install relays for the head lights and spot lights, and will most likely wire in a spare in case I want to mount extra lights one day.
    The question however is there are spare relay slots in the fuse block and I'm trying to figure out how to use them instead of mounting relays separately behind there. Has anyone tried to do this before? (or any tips on understanding the wiring diagrams?)
    I have done all this before in my '77 deluxe Bay, that was much simpler though as the spare relay positions had no cabling prewired behind it, I simply installed my own wiring. In the T3 though there is wiring already there, and cables from behind where the relays are goes back to the plugs behind the panel. I don't want to mess with that wiring in case it affects something else in the system.

    Next question, when I pull the fuse block out, there is a relay behind it (mounted to the body above and to the left of the fuse block). It's marked VW Audi and the wiring all looks factory (my bus has not had any doctoring done to it by previous two owners). I can't figure what this is for. Any one have any ideas?

    Last question, I was looking at the spare bulb location in the rear lights (for fog lights) and was thinking it would be nice to run 4 tail lights instead of 2. The simplest way to run it would be bridge the fog light and tail light pins on the connector, but not sure if this affects any other wiring? Alternatively does any one know where the fog light cable terminates under the dash so I can connect that up instead?

    Thanks,
    Richard
     
  2. nils

    nils Well-Known Member

    Messages:
    1,467
    Location:
    newcastle
    I have messed with my wiring quite alot, and can tell you there are 3 relays that are easily useable. I will scribble up a mud map for you during my lunch.
    . The easiest two use the 2 rectangular plugs on the rear of the fuse panel (one 2pin,the other 4pin) the 2 pin in hard wired to hot and has an input and output (handy!) the 4 pin I will have to chech diagrams. Both of these require plugs that are the same as those used in your centeral locking loom.
    The third is a bit more of a pain, requiring you find the correct 3 pins in the back of the existing plugs
     
  3. syncro

    syncro Well-Known Member

    Messages:
    9,557
    Location:
    Southern Highlands
  4. Kombi Dad

    Kombi Dad Well-Known Member

    Messages:
    2,428
    Location:
    Bungendore, NSW
  5. Grantus

    Grantus Well-Known Member

    Messages:
    16,349
    Location:
    Southern ACT
    Does the fog light bulb holder have a contact pin for the active end of the bulb in your tali light housing?
     
  6. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Thanks all, great information, can't wait to give it a go (along with H4 +130 and H3 +100 bulbs!).
    I have not traced the cable from the battery to the fuse box yet, but was thinking I might piggy back an extra cable in parallel so have greater capacity there also. I found that to help a lot in the Bay window (battery is in the back)
    I assume the cavble from the battery goes straight to the fuse box somewhere before branching out?

    Grantus, I only saw there was a contact at the back of the bulb holder/socket, I have not removed the plug to confirm there is a pin there, sounds like I better look. I'm guessing not all have the pin?
    If I can get that working, I might look for some nice LED bulbs to put in there also. Am waiting on a couple of (hopefully) bright ones for the reverse and brake lights.
    The stock 5W bulbs are quite dull.
    Richard
     
  7. nils

    nils Well-Known Member

    Messages:
    1,467
    Location:
    newcastle
    wiring mud map as promised, Just a heads up 7 is what the factory used for the fog lights.

    relay 7 - A24 is the sensor wire, B20 is the whatever you are trying to power
    relay 1 - R1 sensor, R2 power out
    relay 6 - just wire to match your relay you are using, I think the negative may already be present, but don't quote me on that
    [​IMG]
     
    Last edited: Aug 5, 2015
  8. Grantus

    Grantus Well-Known Member

    Messages:
    16,349
    Location:
    Southern ACT
    Not at the plug - at the bulb holder. My original Hella tail lights had the holder to hold the bulb, but no contact in the holder for the active wire to the base of the bulb.

    Hope that makes sense....o_O
     
  9. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Thanks Grantus, yes your right the contact is not there, so I will tackle this another time. Looks straight forward to make up a contact and connect it to the tail light wire.

    Thanks Nils, that looks great, and probably the way I will head. I have a trip next week, so will get to this another time, all this info will make it simpler!

    Does anyone have a suggestions for a good workshop manual? I have a Bentley, but the wiring looks quite different to what I have!

    This is the relay I mentioned before, looks like it's for the radiator fan, and has fuse on the side (power direct from battery)

    relay.JPG

    Anyone know what the fuse in the top left is? Power to it is direct from battery There's also an unused fuse holder above relay 42??

    fuse box.JPG

    As best I can tell there are only two wires from the battery, one goes to the fan relay (top image), the other goes to a plug in the back of the fuse box (roughly bottom left as you look at the above image)
     
  10. nils

    nils Well-Known Member

    Messages:
    1,467
    Location:
    newcastle
    Got my manual from eBay on a CD, cost $20 I think. Find myself printing alot of pages, but am very happy with it.
     
  11. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Finally getting back to the wiring!! Got side tracked and never got back to it last year.
    Interesting measurements on voltage. With high beam on I had 11.7V at the battery (engine off) and 8.1V at the head light/spot light!!
    I have split the earth cables only so far (each light now has it's own earth, this gained 0.6V !!
    Am thinking of running three relays, one for both low beam, one for high beam (left) and one for high beam (right), and I have added two additional 10 gauge cables to the front as well.

    Out of interest I also looked at voltage across the radiator fan as I noticed earth for this runs back two the little earth tree's. I left the original cable there and ran an additional earth cable to the chassis.
    Again engine off, fan running, 11.7V at battery, 4.5V across the fan (low speed, so after the load resistor). With new earth cable voltage was 5.1V

    Shows just the original cabling was a bit lacking!
     
  12. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Hi Nils,
    Thanks again for the relay connections. As much as I wanted to use them, I have decided to run the lights off their own power cable separate to the stock wiring, So for ease of connection I will mount a bank of relays separately with their own power direct from the battery, but still use the factory fuses and cables to the lights.
    The high beam to each side could do with a larger cable, but I will leave this as is for now. Progress on wiring as I clean up under the dash a little. 27 years of dust build up under there needs to go!
     
  13. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Another question for the wiring guru's. I have tired to make sense of the Bentley wiring diagrams but they still leave me at a loss.
    Does anyone know the wiring to the ignition switch? There is the main power in (red), but there are 5 cables coming out. Anyone know which is which?
    There are two larger cables, back with yellow stripe and red with black stripe. Anyone know what they are for?
    Black with yellow strip seems to go back to the fuse panel. The red with block strip, is that the starter maybe?
    While I'm adding relays might be worth isolating these two high power cables to take load away from the switch.

    There are also two block and one grey cable??

    Thanks!
     
  14. peter915

    peter915 Active Member

    Messages:
    707
    Location:
    Sunshine coast
    Andy
    A basic VW wiring diagram can be found here
    It's not the same exactly as a T3 1989 VW but it will give you some idea
    Central pin in the drawing (ignition key - round circle) is the battery - positive
    Turning the key selects the terminal and supplies power to this terminal
    Hope that helps?
    http://i63.photobucket.com/albums/h160/USMCord1/tech/Basicwiring.jpg

    And give me a call for any LED light requirements
    Peter
     
  15. Syncro27

    Syncro27 Well-Known Member

    Messages:
    6,252
    Location:
    Terrigal, NSW Central Coast

    That fuse holder is for the central locking.

    I think they wired these vehicles for everything and every option but only installed the main parts if you paid for it.

    My van has been wired how you mentioned with the "Piranha" relay system with the relays installed just behind the headlights.

    My headlights work fine but my high beams still don't and I have looked at a few areas with no problem areas son fa.

    I got some relays of Lucky Phil today (thanks Phil) and I will give them a try later.
     
  16. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Thanks Peter, that helps! I assume the black with yellow is ACC, red with black is starter.
    So a relay on these two will help the ignition switch.
    Thanks also on the LED's. I have already done the reverse lights, but was planning to do the parking lights, tail lights and brake lights next!
    Indicators looks a bit more involved, not really keen to change the relay as I regularly tow trailers and have no control of what lights they have.
    Richard

     
  17. Andy.

    Andy. Active Member

    Messages:
    498
    Location:
    Brisbane
    Thanks Scott, good to know that fuse then! Yes there is a lot of stuff in there pre-wired as well as a lot of cables with plugs behind the fuse panel not connected. Be nice to know what they all are!
    I thought the best one from Vw was the intermittent wipers, just remove the plastic clip preventing the wiper stalk selecting it and away you go!!

    How do the relays behind the head light go? Thought the rain would affect them. The earthing has definitely been a big help, so worth looking into.
    Another thing to look at is cable sizes, I have run my own cables for some parts. The relays I bought look fine, rated to 40A (I will run ~10A through them), but the pre-wired cables in the relay base were tiny, way under sized for 10A let alone 40!! I ripped the pins out and soldered in my own heavier cables there also.
    Richard


     
  18. Syncro27

    Syncro27 Well-Known Member

    Messages:
    6,252
    Location:
    Terrigal, NSW Central Coast
    Yes Richard,

    I am of the opinion that my relays are probably toast from getting wet.

    I have seen this system in one other van - a syncro which got a lot of wet weather and off-roading use and the only thing that failed was the fuse blew when he upgraded the globes to higher power ones.
     
  19. Kombi Dad

    Kombi Dad Well-Known Member

    Messages:
    2,428
    Location:
    Bungendore, NSW
    Totally agree. I had to pull it on my way to Melbourne recently as the central locking in the '89 kept cycling.

    Ian
     
  20. peter915

    peter915 Active Member

    Messages:
    707
    Location:
    Sunshine coast
    Andy
    Hope the drawing helped
    I have a indicator flasher relay which is LED compliant and seems to also work with standard filament bulbs
    I also carry the complete range for the T3, including both headlights (square) or round single in CREE, plus the parkers and interiors.
    My CREE headlights don't need upgraded wiring or relays as they use less power than the OEM bulbs
    Also, I'm trying to find the time to develop a LED replacement kit for the T3 tail light cluster, making use of the blank red fog light lens which is not used here in Oz.
    Peter
     

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