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    Thread: Relay Question

    1. Junior Member
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      Jul 7th, 2010
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      1983 GTi 16V
      01-23-2011 02:38 AM #1
      So I just replaced my fusebox since the PO had ghetto-wired a fair bit and melted portions of the one that was in the Rabbit. A few questions:

      Going by the diagram in the Bentley the fuel pump relay should be in the upper left corner of the box, on one of the little relay attachments. My old box had no relay there, and the new one was missing some stuff when I pulled it at the junkyard so there may or may not have been one there.

      My old box had no relay in what Bentley calls the upshift control relay but the PO had used a wire to jump two terminals, which in turn melted the area. I have a couple extra relays from when I pulled the new fusebox, which relay should go there? I can't find anything that specifies aside from "whatever fits the pins". It is the first relay on the top in this picture, the one with the wire in it.



      Finally, what does the blue plug go to? Aside from the first column of fuses being one row low does anything stand out with the new fuse box as wrong? These are all the relays that were in the car before, it was empty in the upper right box as well as the oil pressure relay and only had the little metal jumper between pins 50 and C in the interlock/warn one.


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    3. Member VWCaddy's Avatar
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      1982 VW Caddy
      01-23-2011 01:54 PM #2
      This may be of help if you have not seen it:
      http://www.4crawler.com/Diesel/index.shtml#RelayPanel

      '82 diesel pickup, Missing LinkZ custom shift linkage, Quaiffe transaxle, Bilstein shocks F/R.

    4. Junior Member
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      1983 GTi 16V
      01-23-2011 06:52 PM #3
      Thanks that does help The Bentley shows 6 relays (one being the taped one) and says that the fuel pump should be the top left. Yours matches mine much more closely, although I am not sure how it was running with no fuel pump relay. I will have to go check for more crappy wiring, maybe the PO did something with it as well. Is the upshift relay just for the little "shift up" light, or does it have to do with auto trannies? I don't really want the light and have a 5 speed, so I'll see how it runs with nothing there for now.

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    6. Member VWCaddy's Avatar
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      1982 VW Caddy
      01-23-2011 09:19 PM #4
      On the diesel, the upshift light is just for the light on the dash, I think it is similar on the gas engine.
      '82 diesel pickup, Missing LinkZ custom shift linkage, Quaiffe transaxle, Bilstein shocks F/R.

    7. Member cuppie's Avatar
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      88 Scirocco 16v (Wilda); 02 Passat 1.8T wagon (the Brick); 09 Jetta Sportwagon (wife's.) Past: lots
      01-23-2011 09:25 PM #5
      ^ ^ ^ That would be exactly correct. A/T cars don't have the upshift-light relay (which is why it's missing in the diesel-automatic legend.)
      On a stick, all that relay does is control the upshift indicator in the cluster. Pulling it won't affect (negatively) engine operation one bit.
      - Cup
      '88 Scirocco 16v, 'tastefully' modified.
      '02 Passat 1.8T (The Brick.)
      things currently broken (Scirocco): 4
      things currently broken (Passat): 2

    8. Member
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      2004 Flash Green V70R
      01-23-2011 10:41 PM #6
      About the fuel pump relay: read the scan above carefully: There are 2 different fuseboxes with a change in late 82 or early 83. One has the fuel pump relay on the panel itself above the X relay and the oil pressure relay is on the top row above the fuse panel. The other has the positions switched with the oil pressure relay on the panel and the FPR up above.

      If you look on the face of the relay and fuse panel (where the fuses are not the top row of relays above) there are the names for all the relays molded into the plastic. They are hard to see but they are there. So the open socket you have on the middle right is supposed to be either the FPR or the oil pressure relay. Look at the panel and see what it says.

      Remember the fact that this was an 82/83 change doesnt mean much because VW replaced lots of fuseboxes under warranty so it could be either kind.

      The blue plug is likely the rear speaker harness plug and likely isnt connected to anything.

    9. Junior Member
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      1983 GTi 16V
      01-24-2011 02:53 AM #7
      Did some fiddling with it earlier, and the middle right relay socket is for the oil pressure relay. Also I found that my fuel pump relay socket is where auxiliary relay 1 is in the diagram listed. Car just dry cranks with nothing there. The other 5 pin relays have the small pin facing the wrong direction so they will not fit. I will have to see about picking up a new relay tomorrow to fit in there and get running again. Interestingly, my oil pressure light has always worked even though there was never a relay plugged into the socket. Is the relay for something else pressure related other than the LED?

      Good to know about that blue plug, since somebody took my rear speakers out, and I have no head unit right now, I can go ahead and pull that wiring as well.

    10. Member
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      2004 Flash Green V70R
      01-24-2011 10:26 AM #8
      You can use the horn relay temporarily in the fuel pump relay socket to see if the pump works. BUT dont use one permanently like that. If you use a standard relay like this the pump will come on anytime the key is on.

      A correct FPR will prime when the key is turned on. Shut off until you crank and then only stay on while there is a rpm signal from the engine. It does all of this for safety reasons. So make sure you get a correct FPR at some point.

    11. Junior Member
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      1983 GTi 16V
      01-28-2011 04:01 AM #9
      So I tried using the horn relay temporarily to run the car. With the horn relay in, KOEO I can hear the pump run for a few seconds, then shut off for a few seconds. It cycles back and forth like this. KOER it runs for a few seconds then shuts off; I am assuming the relay is shutting off in its cycle. After the car dies the relay starts clicking rapidly until I turn the ignition off.

      I bought a new fuel pump relay and put it in, nothing. No priming, no fueling at all.

      I can jump the top and right pins and it runs just fine, runs the pump with KOEO and KOER; this is how the PO had it rigged and obviously I want it to run with a relay like VW intended.

      I noticed another relay issue when I drove it around jumped temporarily to make sure everything else worked. Before I changed the fusebox the oil pressure relay was empty. When grabbing my MK2 rear seat to swap in at the junkyard I picked up a relay from the MK1 there to put in my oil pressure relay spot. Even without the relay, the oil pressure LED always seemed to work, it would come on when I first started the car and go away when the lifters quieted down. With the relay in there, the light comes on and a buzzer goes off at 2200 RPM or above. Just out of curiosity what RPM is the shift up light supposed to come on? I don't put it past the PO to have mixed up the wiring.

    12. Member
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      2004 Flash Green V70R
      01-28-2011 11:09 AM #10
      If the OEM fuel pump relay and the oil pressure relay are acting like that then you might have a problem with the tach signal from the coil. The oil pressure relay and the fuel pump relay (and upshift light relay) use engine RPM as a signal. So thats one thing to trace and check if it is getting a tach signal when the engine is cranking or running.

      When using the horn relay the pump should be on all the time when cranking or key on.... so if it is dropping out you have something that is causing that like a bad ground, bad ignition switch, a short or bad connection somewhere. What you are saying with it dropping out with the relay but not when jumped indicates to me that the ground for the relay is bad. All of the grounds are tied together in the back of the panel and go to a small pigtail that has a sheet metal screw in the firewall. You must make 100% sure that pigtail is grounded and SOLIDLY even if you need to use a bigger screw. If its not all sorts of weird stuff happens.

    13. Junior Member
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      1983 GTi 16V
      01-28-2011 03:08 PM #11
      I will go through and check my grounds today. I have suspected a poor ground for a while now due to the fact that my CLT and fuel gauges always show low; with a full tank of gas and a fully warmed up vehicle they show about 1/4. Also a few time my tach has not worked. I checked the engine bay grounds a while back but haven't done anything with the in-cabin ones.

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