Grounding

[Super65lark]

Hi all,

trying to trace a bad ground. My symptom is: My left turn signal on the dash appears dimmer than the right turn signal. same goes  when viewing the parking lights up front, and the taillights. What is this telling me, and where's the best place to start looking for this bad ground?

[Brian]

Start with the bulb socket in the front turn signal housing. Those are notorious for causing issues like this.  Next look at the bulb sockets on the rear taillights since they would be second in line for causing this kind of problem.

[yachtsmanbill]

Arent the sockets crimped onto the housing providing a ground through the chassis? That crimp is the fail point, then on to the mounting bolts.I'd suggest an ohm meter reading between the socket and the shell to prove continuity. Then from the shell to the cars chassis.

 Its too bad there isnt a conversion to the later style with a dedicated ground wire to the plug.

If it came down to it, cant you solder a wire between the socket and the housing as a stop gap repair (as in all 4 corners?).    Bill

[Loren At 65GS]

Hi all,

trying to trace a bad ground. My symptom is: My left turn signal on the dash appears dimmer than the right turn signal. same goes  when viewing the parking lights up front, and the taillights. What is this telling me, and where's the best place to start looking for this bad ground?

 I could be out in left field here, but the difference in the dash light brightness doesn't make sense to me. Because everything in the dash assembly has the same ground.
As both Brian and Bill have noted, there are multiple points in that circuit to have a poor/weak ground. In the front, the bulb ground goes through the shell of the socket to the signal housing via the crimp of the socket to the housing. Then from the signal housing to the mounting plate attached to the back of the bumper , via the stud and nut that attach the signal housing to the mounting plate. The ground then goes through the bumper bracket to the chassis on to the body and then to the engine via the ground strap at the back of the engine. The ground then travels back to the battery via the ground cable. Your ground could be weakened at any of the bolt points as well as the socket. Keep that in mind, because there could be corrosion at a bolt point causing the weak ground.
 Another thought , the turn signal power goes through the switch in the column, that's how the left and right sides are separated. If you have the slightest amount of corrosion at any of the power side connections there could be a voltage drop causing the dimmer lights. That may be why the difference in the left and right sides. There is a half round connector towards the bottom of the column. Check that connection point. Those terminals can be cleaned using electrical contact cleaner and an abrasive like a scotch brite pad.
 The tail lights are another beast in themselves. Just my opinion, but the way the engineers designed that was poor at best. Relying on the socket to maintain a good ground just doesn't work for the tail lights. When I build a tail light harness, I integrate a ground wire that is soldered onto the sockets and daisy chains through all the lights back to a grounding point in the trunk. There it is attached to the body shell using a screw. Doing this means the bulbs will light up even if the socket becomes dislodged from the tail light housing.

  Good hunting,
  Loren