A 1988 Ford Thunderbird came in with a no charge condition and the alternator had already been changed. Although the following post is about a Thunderbird, the Mercury Cougar has the same failure. Testing at the alternator found that there was no ignition power on the light green wire with a red tracer at the voltage regulator connector. After consulting a wiring diagram I found that the power comes from the ignition switch through the instrument cluster and then to the alternator. I also realised that the instrument cluster itself was dead.
The customer had already had the covers off of the steering column so I went right to the ignition switch.
Where I found this.
I installed a new connector by first swapping the undamaged wires from the old connector to the new one. To order a new repair harness please click here.
I then spliced the new wires with terminals to the old damaged wires. Notice how the splice joints are staggered for a better fit.
Heated the heat shrink tubing.
I replaced the old damaged ignition switch with a new switch. The two torx headed bolts had to be removed to change the switch.
Now, the instrument cluster works and the alternator charges.
So Yeah I have a 1991 Mercury cougar with the same problem instead it is a light green/red voltage regulator wire that kicks in the alternator once in direct contact with battery but it will drain the battery if on for 2 hrs. So Im here to ask what to do and if what replacement parts with links?
I would need to know what engine came in your 1991 Cougar?
Do you guys know where i can buy this green/red wire
There is a link in the article to buy the repair harness kit for the ignition switch. However the green/red wire that connects to the alternator runs from the instrument cluster to the alternator and cannot be purchased.