renrut Posted January 29, 2006 Report Share Posted January 29, 2006 I have a 1956 TR3 and I am in the process of rebuilding it to running condition. I have an electrical problem that more than a few of you have run across. While removing the old wiring harness, I noted a "strap" from electical control modul to fuse holder directly below. This "strap" did not appear on any of the scematic diagrams that I have. I continued to very carefully rewire according to scematic (with a pre-made purchased harness) making sure that every connection was cleaned and working. New modul, new wires new battery and a few new switches. After putting it all together, the only thing that works are the head lights. I have tested the ignition switch to be sure continuety, however, when switched on, the indicator light does not come on. Could there be a lack of continuety between the dash board panel and the ground (positive). Can anyone think of a reason there would be a strap wire from module to fuse holder? Quote Link to post Share on other sites
unclepete Posted January 29, 2006 Report Share Posted January 29, 2006 What about the earthing strap from the nearside front engine mount to the chassis? Double check you have a good condition braided cable fitted. This isn't shown on the wiring schematics but is very important. Will give you all sorts of wierd electrical symptoms if not fitted or damaged! Unc Quote Link to post Share on other sites
Menno van Rij Posted January 29, 2006 Report Share Posted January 29, 2006 First, my knowledge of car electrics is very, very limited. All know is by trail and error (a lot of error...), so, don't be offended when all my tips are way below your own knowledge! Where was the strap you mentioned connect exactly? Perhaps there's a pic or diagram that you can post. On the other hand, there's more to the harnasses than the diagrams show. We all know about the wiring of the wipers. And the other day I read about a fuse behind the dashboard panel, only issued on USA cars! I didn't see that on the diagrams I've studied. As I'm writing this, I don't have a car nore diagram available, so, I write this from memory. There are two fuses. One for the lights. and one for -let's just say- for everything else. there are a number of green wires attached at the secured side: fuel gauge, wipers, indicators, heater motor. Disconnect them and just start by replacing the fuse and cleaning the connectors. After you 've done that, connect them one by one and see what happens. (The wiring diagram of a Spitfire MK1 is almost the same as the diagram for a TR, perhaps that a Spit's diagram will make things easier). You wrote that the ignition light didn't come on. Did you check for the obvious thing: is the light okay? (It's just something that would happen to me, you see). There are also numberous earth connections behind the dash. Be sure that they all work properly. About a year ago there was a fully restored panel for sale on eBay with detailled pics of the back side. I didn't bid, but downloaded the pics. And yes, they were very useful. I can send you a clear pic showing the back side of a dash panel. Menno Quote Link to post Share on other sites
Menno van Rij Posted January 31, 2006 Report Share Posted January 31, 2006 Here's the pic of the backside of the dash. Menno Quote Link to post Share on other sites
renrut Posted February 5, 2006 Author Report Share Posted February 5, 2006 What about the earthing strap from the nearside front engine mount to the chassis?Double check you have a good condition braided cable fitted. This isn't shown on the wiring schematics but is very important. Will give you all sorts of wierd electrical symptoms if not fitted or damaged! Unc I don't recall, but I will check it, seeing a braided strap between the engine and the chassis. That could explain why I can get the engine to turn over by jumping the poles on the starter connection but the engine won't fire. You may just have hit on the problem. A Big Thanks. I'll post later this week and let everyone know what I found. Quote Link to post Share on other sites
renrut Posted February 5, 2006 Author Report Share Posted February 5, 2006 First, my knowledge of car electrics is very, very limited. All know is by trail and error (a lot of error...), so, don't be offended when all my tips are way below your own knowledge! Where was the strap you mentioned connect exactly? Perhaps there's a pic or diagram that you can post. On the other hand, there's more to the harnasses than the diagrams show. We all know about the wiring of the wipers. And the other day I read about a fuse behind the dashboard panel, only issued on USA cars! I didn't see that on the diagrams I've studied. As I'm writing this, I don't have a car nore diagram available, so, I write this from memory. There are two fuses. One for the lights. and one for -let's just say- for everything else. there are a number of green wires attached at the secured side: fuel gauge, wipers, indicators, heater motor. Disconnect them and just start by replacing the fuse and cleaning the connectors. After you 've done that, connect them one by one and see what happens. (The wiring diagram of a Spitfire MK1 is almost the same as the diagram for a TR, perhaps that a Spit's diagram will make things easier). You wrote that the ignition light didn't come on. Did you check for the obvious thing: is the light okay? (It's just something that would happen to me, you see). There are also numberous earth connections behind the dash. Be sure that they all work properly. About a year ago there was a fully restored panel for sale on eBay with detailled pics of the back side. I didn't bid, but downloaded the pics. And yes, they were very useful. I can send you a clear pic showing the back side of a dash panel. Menno Thank you. Good suggestions all. To answer what I can at this point. I used a dry cell 9v battery to test all the lamps as they were placed in their locations. tail lights, dash board lights. We have a parts car (TR3A wide mouth) which I salvaged the old dash. That gave me a few switches and bulbs etc. As I salvaged them I tested each. The bad ones I just tossed in the trash. I ran a single earth connection from a nut on the dash to a location behind the heater near the primary connection to the battery. I did make sure my connections were clean and tight. The dash panel itself was surrounded by a vynal covering similar to the seats. Perhaps I should run additional earthing straps between the sections of the dash????? I printed the photo of the dash below, and will check that against the one mounted in the car. I am getting quit good at wiggling under the dash. As of now the transmission cover and seats are still removed, although the cover is painted and waiting until I get the electrical problems solved. The strap I mentioned in my original post had been painted over by previous owners. It was about three inches in length (15 centimeters) It was not colored to match any other wires so I suspect that somebody had added it at one point in time (coupled with the idea that it didn't appear on any diagrams that I have (2)) I removed the fuse holder and but it into my paint blaster. I use aluminum oxide granules under compressed air to remove paint/rust from the parts prior to my repainting them. It cam out nice and clean. I took solvents to clean the fuses themselves. I put on a new electical control unit. I still have the old. I remounted the cleaned fuse holder and checked with a volt ohm meter to ensure continueity across each connection. I don't recall the exact connections on the strap, but it did run vertical between the control and the fuse holder. Sorry I can't be more exact. Neither my original or salvaged dash panel appears to have a seperate fuse holder or fuse. Could anyone be more descriptive in where I would find one? I am assuming that this is a USA car. Perhaps I can find some holes in the panel which would indicate its removal in times gone by. Thanks again for your suggestions. I will get back with everyone when our weather clears and I have time to work on the TR3 again. Mike Turner (renrut) Quote Link to post Share on other sites
unclepete Posted February 6, 2006 Report Share Posted February 6, 2006 Mike Check continuity from the earth connection side of each instrument bulb etc to the engine block. If the engine has been removed at some time, it may be the engine earth strap has not been replaced. Lift the bonnet and look at the front left engine mount. There should be clamped to the engine mounting plate an earth strap the same size as the one on your battery, this earth strap should then be clamped to the chassis engine mount bolt. The engine mountings are rubber and all this earthing strap does is ensure continuity across the mounting back to your battery with a strong enough cable to cope with current loads through your starter motor etc. Other than the fuses I have added there are only 2 fuses on a TR3 both under the bonnet next to the voltage regulator. I am not sure what fuses you are trying to find behind the dash? Unc Quote Link to post Share on other sites
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