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No O/D in 3rd
- Thread starter MadRiver
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If it consistently functions in 4th and not in 3rd, then it sounds like you are having problems with 3rd-4th gear lockout switch located on the side of the gear shift lever seat. Isolate the switch and put an ohmmeter on it to check for continuity while shifting through the gears (car not running and ignition off). You should show full continuity when in 3rd and 4th gears only. All other gears should show open. You can get to the switch without removing the trans tunnel from underneath the car with small hands.
Good luck,
Mark
Good luck,
Mark
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As Mark said, the 3&4 switch is a spring loaded plunger that is operated by the shifter left-right position. The amount of switch plunger movement that operates the switch contacts can be adjusted by shim/washer thickness between the switch body & the mounting hole shoulder that it screws in to.
Sometimes due to slight wear the switch needs to be moved closer - set deeper into it's mount by decreasing the shim thickness. This switch "could" be not screwed in tightly & giving lost motion.
Any time that the shifter is moved from the 1-2 side to the 3-4 side the switch should make firm contact & hold it as the shifter is moved from three to four.
If adjusting the switch mount depth doesn't help, a new switch may be called for. Sometimes the switch contact block gets loose from the metal housing that it is crimped in to. A good epoxy can tighten/glue the contact block to the housing.
D
Sometimes due to slight wear the switch needs to be moved closer - set deeper into it's mount by decreasing the shim thickness. This switch "could" be not screwed in tightly & giving lost motion.
Any time that the shifter is moved from the 1-2 side to the 3-4 side the switch should make firm contact & hold it as the shifter is moved from three to four.
If adjusting the switch mount depth doesn't help, a new switch may be called for. Sometimes the switch contact block gets loose from the metal housing that it is crimped in to. A good epoxy can tighten/glue the contact block to the housing.
D
Ed_K
Jedi Knight
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Hi,
I just finished trouble shooting my intermittent O/Drive problem a couple of weeks ago.
I found my original 3-4 switch was reading 4 to 5 ohms . Also the transfer switch inside of the O/drive solenoid was not working at all so the pick coil was never energizing. Apparently the hold coil was enough to get it working most of the time.
A new 3-4 switch should read 1 ohm or less. A good solenoid ready to be energized should be less than 1 ohm.
To check these out, you don't even have to crawl under the car. Just unfasten the wire from the o/drive relay and attach one lead of your ohm meter. Fasten the other lead to a good ground. When you move the shift lever to the 3 or 4 position, the switch should make and you should read something less than 4 or 5 ohms total resistance through both the 3-4 switch and the solenoid. Before I replaced the bad switch and solenoid, I was reading 27 ohms. On your car, you should get the same ohm reading in either 3 or 4th. If not , the 3-4 switch is either bad or not adjusted right. If you don't get a total reading using this method of less than 4 or 5 ohms when in either gear, then you have either a bad switch or solenoid or both. You could also have a bad ground.
Happy troubleshooting,
Ed
I just finished trouble shooting my intermittent O/Drive problem a couple of weeks ago.
I found my original 3-4 switch was reading 4 to 5 ohms . Also the transfer switch inside of the O/drive solenoid was not working at all so the pick coil was never energizing. Apparently the hold coil was enough to get it working most of the time.
A new 3-4 switch should read 1 ohm or less. A good solenoid ready to be energized should be less than 1 ohm.
To check these out, you don't even have to crawl under the car. Just unfasten the wire from the o/drive relay and attach one lead of your ohm meter. Fasten the other lead to a good ground. When you move the shift lever to the 3 or 4 position, the switch should make and you should read something less than 4 or 5 ohms total resistance through both the 3-4 switch and the solenoid. Before I replaced the bad switch and solenoid, I was reading 27 ohms. On your car, you should get the same ohm reading in either 3 or 4th. If not , the 3-4 switch is either bad or not adjusted right. If you don't get a total reading using this method of less than 4 or 5 ohms when in either gear, then you have either a bad switch or solenoid or both. You could also have a bad ground.
Happy troubleshooting,
Ed
OP
Offline
Hi guys! I drove the BJ8 again today, and played around with O/D in third. When I shift into third, the O/D doesn't work unless I push the gearshift lever up further than it would normally sit in third, and then hold it there. I feel slight pressure pushing back when I hold it in place. If I hold it in place, it shifts in and out of O/D using the switch quite nicely.
I assume the problem is indeed the lock-out switch? I've looked through the Moss catalog, and can't find the part in question (in case I need to replace it). Could anyone help me identify it, please? Is it #117 on this page?
Moss Center-Shift Gearbox Exploded View
My apologies -- I've never really played around with the overdrive. The O/D works perfectly on my MGC and my BT7, so I'm a newbie!
Thanks guys!
I assume the problem is indeed the lock-out switch? I've looked through the Moss catalog, and can't find the part in question (in case I need to replace it). Could anyone help me identify it, please? Is it #117 on this page?
Moss Center-Shift Gearbox Exploded View
My apologies -- I've never really played around with the overdrive. The O/D works perfectly on my MGC and my BT7, so I'm a newbie!
Thanks guys!
Offline
Yes - Item #117. You do sometimes need to adjust the depth of switch engagement with the thickness of washer #118.
D
D