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BJ8 Overdrive Issue

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SteveHall64Healey

Jedi Trainee
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The overdrive on my BJ8 engages correctly in 3rd and 4th gear, and remains engaged until the switch is turned off. The issue is that it disengages the instant the switch is turned off, where it is supposed to remain engaged until the throttle is depressed by approximately 1/3.

I have disconnected the electrical leads from the throttle switch and verified that it gives about 1-2 ohms with the throttle off and then changes to infinite resistance when the throttle is depressed to approximately 1/3.

Any ideas on what could be wrong?

steve
 
Holding relay issue
 
Most likley may be that there is a bad connection from the throttle switch to the overdrive relay at w1 or C2 terminal. The overdrive relay, next to the throttle switch, gets power to stay engaged in 2 ways. From the battery, power goes to C1 on the overdrive relay which is one side of the contact points in the relay. The battery power also goes to one side of the overdrive switch. When you flip the OD switch it energizes the coil in the relay and closes the contact points Power to W1. That action sends power to C2 through the normally closed throttle switch and thence to W1 on the relay, the same place that closing the overdrive dash switch sent power to close the relay by energizing the coil. The coil says energized even when you flip the OD switch to off. So I suspect since your gearbox switch seems to work and your solenoid works that you have a bad connection from or to your throttle switch. Find out if the wiring connections to your throttle switch, which may also be operating normally as you say , are good on the terminals they go to. If there is a bad connection you wouldn't know if you had a bad throttle switch until you try to use it to drop out of overdrive, in that case flipping the switch would show the problem you have.
 
I've tried to post the wiring diagram to go with my narrative but it is not being cooperative. Not sure what I'm doing poorly. Apologies.

Jon R.
 
Well, this is embarrassing. Jon, in response to your post, I checked all connections between the throttle switch and the solenoid. I recently purchased a good wiring diagram from Tom’s Import Toys, and used it this morning to verify that the connections were properly made. I found that C1 and C2 were wired in reverse order. Swapping them around, the OD system works as expected. Thanks Jon - I love zero-dollar repairs!
 
Great. Some retired guys do soduku, tai chi or crossword puzzles to try and keep an edge. I read the British Car Forum and look for questions that I might help with. I like zero dollar fixes as well. My favorite was when we had an old wood shed that we kept a tractor in and one day the back wall got blown down in a big wind storm. Fortunately the shed remained standing. Because I procrastinated long enough, another wind storm happened and, yup, it blew the wall back into place long enough to secure it. Like it never happened. Some days you're the windshield and some days you're the bug.
 
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