View Full Version : TR4/4A TR4A Gauge Light Question

03-13-2012, 09:51 PM
Removed and marked all the gauge wiring when we replaced the wooden dash. Put all the wiring back as marked. Everything lights up except the temp,fuel, and amp illumination lights. There is a three wire ground going to the top stud of the oil gauge, then a common ground wire starting at the temp stud,to the bottom oil stud, then on to the fuel and amp. When we run a jumper from ground to the temp, all gauges light up so we know its a ground issue but cant seem to figure this one out. What are we missing?? Thanks

03-13-2012, 10:47 PM
Ground from the gauges to the chassis?

03-13-2012, 11:59 PM
I think there is supposed to be ground wire from the harness to one of the other nuts on the gauge clamps (maybe the second ammeter one).

Here's a shot of the back of a spare dash I have showing the common ground wire which should go to all 4 gauges. It sounds like yours has been modified slightly.



03-14-2012, 03:07 AM
The original ground wires can get brittle.

The TR4 Manual shows how that grouped "3-wire" ground wire attaches, and I think you're correct that it attaches to the oil gauge. I can verify and send a pic tomorrow if you still need it.

However, the important thing is that the "four wire hoop" that goes to all gauges and shown in Scott's photo be checked to be sure that each eyelet is intact and the the wires not broken or corroded. On mine, the eyelet that went to the fuel gauge was broken. It appeared OK but it was not.

03-14-2012, 06:06 AM
We also think the culprit is the "3-wire" ground wire. Must be a break or corrosion. Now trying to get it out and repair it is the next mission!

03-14-2012, 08:36 PM
Spent waaaaaay too much time under the dash trying to get the ground wire to work so we finally ran a ground wire from the speedometer ground over too the back of the temp gauge and now all the lights work. Cant figure out why it works but its time to move on to something else.