1997 Gt Convertible - Turn Signals And Top Motor Fails At Same Time?


New Member
Sep 25, 2017
Elderly dad's mustang sat for a couple months and battery went dead. Jumped the car. Then said to dad, "let's put the top down while we drive around and charge the battery." Top went down without a problem. While driving around I noticed that the turn signals were not working. When we returned to the assisted-living facility we couldn't get the top to go back up. Put on parking brake, transmission in P, pushed button and not a twitch or a sound. Went to the auto parts store and replaced the breaker in the interior fusebox. Store put an Ohm meter on the engine compartment relay and it tested good. Eventually, with slow and deliberate force we were able to raise the top manually. Didn't want to do that but impending rain made it a necessity. Back to the turn signals. Turn signals also don't work but brake lights do, except when the turn signal is engaged. That is, both brake lights work except the left brake light won't work when the left turn signal is engaged. Right brake lights work until the right turn signal is engaged. Emergency flashers work. Pretty sure everything worked when it was parked but not certain since it was the first time I have driven the car. Can't help but think the issues are interrelated. Anyone have any thoughts? Thanks
  • Sponsors(?)


SN Certified Technician
Aug 14, 2009
Houston Texas
Can't help but think the issues are interrelated. Anyone have any thoughts? Thanks
You may be onto something. Several parts of the systems you are having problems with use Ground G300 in common. Per the Ford service manual ground G300 is located:

1997 G300 Below rear of center console.

If interested in getting a full set of wiring diagrams and Ford service manual for your car I maybe able to help. PM if interested.

If this were my car I would remove the rear seat to access the raise and lower relays. From the lower relay there's a black wire. Using a Volt-Ohm Meter (VOM) confirm there's a solid ground path all the way back to battery negative.

There are several ways to determine this. One method is to perform a resistance measurement. However this does not confirm the ground's ability to carry a heavy current load. The BEST method is to use the voltage drop method. Here's some information on how to perform voltage drop tests.

Howto perform charging system voltage drop test

The true old school method is to simply find ground G300 and clean it and see if this solves the problem.

Note, I can't help you find ground G300 with any additional informational other than provided. The Ford service manual does have some additional car diagrams that may provide more information.