My 1980 242 M 46 OD stays engaged thou only in 4th.. Could it be a a bad switch on the shifter stuck solenoid ... Shift fine first through third. Then fourth is goes right to overdrive....

Thanks in advance

Yes this the original M46 setup ...No Relay .... Just the slide type switch.... Taking car of it this weekend.. Thanks all

This is the original setup? With the on/off switch and no relay, not the momentary contact switch with relay?

Just by the fact that OD immediately engages on shifting into fourth, it has to be the switch. But that might be intermittent.

That's the only scenario that makes any sense.

Remove the shifter switch and check it for continuity in the off position. If no resistance, there's your answer.



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'80 DL 2 door, '89 DL Wagon

...it has to be the switch. Maybe the wiring at the switch. But that might be intermittent.


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'80 DL 2 door, '89 DL Wagon

I've been warned that the OD should not be engaged when shifting into reverse. That is why post '80 m46's are activated via a relay.

If this is true then it is best to disconnect electrical power to the OD until the short is fixed.
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

edit:

I removed my original reply here because by the time I posted, Volvodad had said what I wanted to say and said it much better.


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'80 DL 2 door, '89 DL Wagon

The fact that his OD only engages when 4th gear is selected means the 4th gear switch is operating properly. Thus, no danger of the OD being engaged in reverse (or any other gear but 4th), even with a malfunctioning switch.

The relay was introduced for a few reasons. One, it takes the electrical current load of the OD solenoid off the little switch. Second, the OD relay toggles "off" whenever you either shift out of 4th, hit the little gear knob button, or shut the ignition off. OD can not be engaged again until the trans is back in 4th at a decent speed, and you hit the button. This prevents OD from being automatically and instantly engaged as you select 4th gear, if you left the switch "on", which is what would happen with the older (no relay) setup.

Both systems employed the 4th gear switch to prevent OD operation in any other gear.
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Bob: Son's XC70, my 83 240, 89 745 (V8) and S90. Also '77 MGB and some old motorcycles