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Wehrle Relays & Main Electrical Loom Diagram

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  • Wehrle Relays & Main Electrical Loom Diagram

    My 2004 Roadsport SV has been experiencing intermittent fuel pump failure, which I’ve traced to loose terminal connections at two Ripca Relf 1 relay/fuse holders. The relay/fuse holders have melted somewhat and caused some pitting to two, 40amp, five terminal, Wehrle relays (part Nos. 02.018B and 02.024B. I don’t know how to test these relays to determine if either has suffered functional damage as a result of external causes, or whether the failure of these relays has been the cause of the melted relay/fuse holders. Thus, while awaiting arrival of replacement relay/fuse holders from Holland, I’ve been seeking to replace the relays. I don’t know what type of relays you replaced, but I’m hoping that you might be able to put me in touch with a source which either, carries Wehrle relays, knows how to get in contact with the manufacturer, or is able to identify an appropriate substitute for the Wehrle brand items. I have attached sketches of the circuitry and terminal layouts of the two (2) Wehrle relays.

    I have sent a dozen emails and faxes to both Caterham USA and UK to zero effect. Further, I’ve found that my assembly manual does not contain the proper wiring diagram for my car. Caterham UK has sent me several additional but utterly useless diagrams, not one of which comes close to matching my factory installed main wiring loom. Thus I also would be interested to know if your vehicle came equipped with five relay/fuse holder modules, containing five relays and fifteen fuses and, if so, whether you have a main loom diagram reflecting such configuration. Any help you can give on the subject of relay replacements or main loom electrical diagrams would be gratefully appreciated.
    Attached Files

  • #2
    I believe the relays are a standard automotive relay. Any auto parts store should have them.

    Someplace on this site I posted what is supposed to be the USA Zetec wiring diagram. I'll try to find it and post again. Found.

    My car is not an SV so yours may be different.

    Where are you located?

    Attached Files
    Last edited by Doug Liedblad; May 20, 2008, 06:07 PM.


    • #3
      FWIW, I have ordered relays and holders from

      They were an identical match for my engine harness. They have an online catalog that you can browse through to see if you find a match for your car.
      Tom "ELV15" Jones


      • #4
        Another source is Vehicle Wiring products. The only place I've found that carries open barrel crimp on terminals of just about any size and type. I like the crimp that this style makes compared to the closed barrel. It crimps the wire better and if done correctly crimps onto the insulation as well.

        They are in the UK, shipping by mail takes about one week and is reasonable.



        • #5

          I got your mail but since you posted here as well, I'll respond here.

          Zentec ( have a 50A Wehrle version in stock and can get you specific part numbers or Bosch/Tyco equivalents. Send an email to micah at, or call them. Disclaimer: Zentec are buddies of mine.

          Doug posted the US-spec wiring diagram as a reply in this thread, and that's the only one (bad as it is) that I've seen.

          /Magnus F.


          • #6
            Turn Signal Relay

            I think my turn signal relay is going bad. It works ok for left, but buzzes when I turn on the right signals.

            I pulled the relay and it is a Wehrle 54 201 101. If I google this relay, I can't really find any suppliers. Does anyone know a replacement that is readily available in the US?



            • #7
              Have you tried standard automotive turn signal relays?

              It may look different on the outside but compare the pins.



              • #8
                You are correct - at a decent autoparts store it was easy to find a replacement - just have to get the voltage and wattage right.


                • #9
                  Did you find one that works OK?

                  If so let us know the number, we can put it in the parts wiki.




                  • #10
                    I did find one at a regular car parts store: 12V and 21 W. Not much to it really.

                    Since the flashers worked properly, using the same relay, I knew the wiring was ok. As it turns out the problem was in the turn signal toggle switch (on-off-on). I don't understand what happened to it, but when I measured resistance, there was none in the direction that worked, but a slight ( ~0.5) in the other. This was enough to not allow the relay to function properly. Replaced the switch with a 20W, also available at local car parts store, and it works great. Weird...