View Full Version : Wiper Problems

02-25-2007, 01:30 PM
I couldn't seem to get my wipers to work (new wiring harness) so I assumed that the wiper motor was the problem. I send my motor off to "British Car Part Restoration" for rebuilding. I received it back and ... still no go! My green wire has been tested and has power. I've tried just about everything or combination of things I can think of. Any ideas?


02-25-2007, 01:42 PM

I thought that Dale (Tinster) had a problem with his wipers after installing a new harness also. He'll be back in here by tomorrow in the event that no one replies on this. You might want to send him a PM to ask if I remembered correctly.


02-25-2007, 02:22 PM

You might want to try a couple of quick diagnostics on your connections:

I assume you have a simple ohm-meter:

Step 1) Disconnect the black wire from terminal 1. This wire should feed to your wiper switch, then ground out. So on the dash, turn the switch 'on', then go and check use the ohm-meter and put one probe on the disconnected black wire, and the other probe on a good metal frame ground. You should read nearly 0 ohms. With the switch off, you should have high ohms. If you don't, you have a problem with this particular circuit - check the switch itself, and also the ground which is after the switch.

Step 2) If that connection checks out, reconnect it, and pull the big black wire. This is also a ground wire, probe test the resistance between it disconnected and the frame - should be 0 ohms again. If not, check that major ground on where it hooks to the body.

Step 3) Reconnect the big black wire, and pull the green black wire off terminal 1 again. Take a separate small wire and temporarily ground terminal 1 to the chassis. As soon as you turn on your ignition switch, I think you will get power to terminal two, and with terminal 1 grounded, your wiper should wipe. If not, you may have a bad motor, or perhaps the whole wheelbox assembly is frozen and it can't move. If in doubt, disconnect the motor from the wiper mechanism and see if it can run.

Anyway, that is probably not worded as well as it could be, but I hope it helps.


02-25-2007, 02:26 PM
According to all of the wiring diagrams I'm looking at, the only wiper motors that had three connectors on them, are for the TR3, TR4, and TR250. All the Tr6's have five wires going to the wiper motor. Also, the Moss site shows that the body of the wiper motor for the TR6 is round and not square. I see you have a '73, and this doesn't make sense.

Anyway, try this...The green wire should go to the #2 terminal. The wire going to the "E" terminal should be a ground. That should be the black wire. Turn on the ignition, and then, with a jumper or screwdriver, ground terminal #2 to the case, and the wiper motor should run. If it runs, then we have to figure aout what's going on with the harness, the wiper motor and the switch.

EDIT: Is this a TR6 we're talking about?? /bcforum/images/%%GRAEMLIN_URL%%/confused.gif Or a TR4???
Your sig said '73 TR6, but I noticed that that car was green, and the one in question is red.

02-25-2007, 02:28 PM

You're spot on with the later style terminals - but this is Larry's nifty TR4. Larry - you need to update your sig picture!

And Larry, use Art's advice, just short terminal 2 to the case - I tried to say the same thing but it took 3 paragraphs!


02-25-2007, 02:52 PM
OK, now that we've established this is a TR4, when you ground terminal #2, if you see some sparks and the wipers DON'T move, then you most likely have a mechanical problem. If they DO move, then the wiper switch or it's grounding is at fault.

02-25-2007, 03:22 PM
Actually, I checked my manual again just to make sure - Terminal 2 should have the hot wire as stated. But terminal 1 is the one connected to the switch and eventual ground. Because of that, I think you need to short terminal #1 to the case, not terminal #2. Basically, your picture looks entirely correct, just test terminal #1 as Art notes.


02-25-2007, 03:58 PM
Do you own a copy of Dan Masters'
Electrical Maintenance Handbook? Good read on
trouble-shooting TR6 electrical issues.

If not, here is the link. Cost $30.


Best of luck,


02-25-2007, 05:35 PM
Traced to a bad ground wire after the switch. Thanks all!

02-25-2007, 06:54 PM
Larry, just for curiosity's sake, from whom did you get the wiring harness from? Was it a plug'n'play deal, or did you have to do much soldering/ terminating, etc. Good luck w/ the '4, looking good!

02-25-2007, 09:08 PM
I bought it from TRF ready to go. On a TR6 there is a front and rear harness and it's important that you buy the correct harness. It's really not that hard to replace an old harness on a TR6 with one from TRF or Moss.