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In a forum thread from 2013 that I found in a Search, Randall suggested making a diode jumper to help protect overdrive relay. I made one with a IN4004 diode at end of the jumper toward the 87 terminal of the overdrive relay. I would like to test the jumper to make sure all my solder/crimp joints are good. When I tried to do a continuity test on the jumper, I got no reading. I don't think I have bad solder joints, but how do I test it to make sure?
Here is Randall's recommendation from the 2013 forum entry:
Your diagram looks good to me; but I'll throw in one more thing. In my experience, although the original relays would stand up to the inductive kickback from the solenoid, modern ones won't. Once the original relay failed on TS39781LO, I went through several replacements (including an expensive reproduction) in just a few months. The cure I found was to add a diode to help absorb the kickback and keep the relay contacts from arcing each time. That was in about 1995 and I'm still using the same cheap junk relay today. Any of the 1N400X series diodes will work fine. (Radio Shack sells a 25 pack "assortment" of 1N400X diodes for $3.50, and I used whatever fell out of the package.) Connect the diode from the load terminal on the relay (87) in your diagram to ground, being sure to match the diode polarity to be opposite of your batter polarity. The diode will have a white stripe on one end, which is the cathode. If your car is the original positive ground, the white stripe goes towards ground. If your car has been converted to negative ground, the white stripe goes towards the relay terminal.
Thanks for the help!
Regards, Bob
Here is Randall's recommendation from the 2013 forum entry:
Your diagram looks good to me; but I'll throw in one more thing. In my experience, although the original relays would stand up to the inductive kickback from the solenoid, modern ones won't. Once the original relay failed on TS39781LO, I went through several replacements (including an expensive reproduction) in just a few months. The cure I found was to add a diode to help absorb the kickback and keep the relay contacts from arcing each time. That was in about 1995 and I'm still using the same cheap junk relay today. Any of the 1N400X series diodes will work fine. (Radio Shack sells a 25 pack "assortment" of 1N400X diodes for $3.50, and I used whatever fell out of the package.) Connect the diode from the load terminal on the relay (87) in your diagram to ground, being sure to match the diode polarity to be opposite of your batter polarity. The diode will have a white stripe on one end, which is the cathode. If your car is the original positive ground, the white stripe goes towards ground. If your car has been converted to negative ground, the white stripe goes towards the relay terminal.
Thanks for the help!
Regards, Bob
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