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Hi. We replaced the engine in my 1973 mustang convertible. Swamped a straight 6 for 351W. The engine isn’t running yet due to several electrical issues.
We are hooking back up electricity and noticed no power to top motor and now the battery has a 12.86V draw. Each fuse was removed and all connections to the starter relay to check the draw. When the black fusible link wire (only was removed) on the battery side (other end goes to the alternator) was removed the draw dropped to below 1V. So what does that mean? Alternator appears to be properly connected.

Also, is the yellow fusible link on the battery side of the relay go to the top motor?

The motor does run when connected to the battery, but it isn’t’t receiving power.
Thx so much, going crazy here🤯
 

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Link to the 7173 site with wiring diagram downloads.


The convertible motor receives power through an accessory feed wire that travels across the passenger side shock tower brace , then through the firewall below the master cylinder. It is connected to the Battery (+) post of the starter solenoid through a circuit breaker. See pic below, highlighted the feed wire and CB in red.

My assumption would be your draw is caused by a failed component inside the alternator.


Motor vehicle Hood Automotive tire Vehicle Automotive design
 

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Discussion Starter · #3 ·
Link to the 7173 site with wiring diagram downloads.


The convertible motor receives power through an accessory feed wire that travels across the passenger side shock tower brace , then through the firewall below the master cylinder. It is connected to the Battery (+) post of the starter solenoid through a circuit breaker. See pic below, highlighted the feed wire and CB in red.

My assumption would be your draw is caused by a failed component inside the alternator.


View attachment 842030

Thanks For the information. On the draw issue, the alternator test is good. Any other suggestions? The car did have significant frame prefabricating ( lots of rust) and the welder possibly did something to the harness that we have not found.
Light Electrical wiring Gas Cable Electronic device


The other end of the accessory feed line has 2 prong type plugs in it with room for a third. (Circled in yellow). Circled in red is the 2 way wiring for the top motor. I’m assuming there should be a prong type plug in that accessory feed line to connect the top power?
 

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Thanks For the information. On the draw issue, the alternator test is good. Any other suggestions? The car did have significant frame prefabricating ( lots of rust) and the welder possibly did something to the harness that we have not found.


Light Electrical wiring Gas Cable Electronic device



The other end of the accessory feed line has 2 prong type plugs in it with room for a third. (Circled in yellow). Circled in red is the 2 way wiring for the top motor. I’m assuming there should be a prong type plug in that accessory feed line to connect the top power?
How many spots on the accessory feed that are used depends on the options in the car. It was used for convertible top, automatic seat back release, power windows, and the power seat in the Cougar. I believe the heavier wire plugged into the 3-way is the power feed to the convertible top switch, and the lighter gauge is the seat back release.

Probe the 3-way for voltage. If it's good there, you can disconnect the red/yellow two way and jumper to either one from the 3-way. The top motor is grounded, so one wire is up, the other is down. If the motor functions from that connector, then you need to look at the top switch. If not, then you need to look at the harness running down the rocker into the trunk.

Another possibility with the draw is the voltage regulator. Hook up the alternator so it produces the draw, then disconnect the 4-place plug on the voltage regulator. The original regulators used mechanical points that can stick and cause a draw.
 
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