Trying to diagnose intermittent OD in/out on the 92 945T.

1. Old relay in up arrow on, no change with OD switch on shifter
2. New relay in, up arrow on, no change with OD switch on shifter
3. Attempted to remove OD switch to test, only got the plastic knob out, the remainder of the switch body remained in the shift knob. Not sure how to get a hold of it to remove. I think it must come out and be unsoldered to remove the whole knob so I'm stuck.

Possible next steps

a. Jumper from relay 15 to relay 87 connections and see if OD arrow goes out
b. Give up on OD in/out and remove OD solenoid and install bypass plate (on hand).

Any suggestions from the board?

Brian Mee

92 945T

I'm staring at the wiring diagram. Jumpering OD relay pins 15 to 86 and re-installing the relay with the dash light now going out is highly suggestive it's the OD switch circuit. This is a stepping relay and the switch is momentary contact, not an on/off switch. The relay resets whenever the ignition is switched off. If the dash light immediately comes on then I'd be more suspicious of the relay than the switch circuit. It could still be the switch, but it would need to be internally shorted. It could also be a short in the switch wiring circuit. The switch wiring coming out at the base of the stalk is subject to flexing and possibly breaking, so a short there is possible, also in the wiring coming out the side of the shifter assembly and where it goes on top of the tunnel to the relay harness connector, especially if there's been recent work in that area.

I'd want to do as much diagnostic testing as I could at the relay tray before going to the trouble of removing the switch. Now if you've already got the switch pulled out then great, that's a second great test point to confirm whether it's the switch or wiring. Whatever you do, don't let the two black wires slip down into the stalk or you may be into an even worse adventure pulling and disassembling the trans shifter assembly to get to the base of the stalk. Be glad you've at least got the earlier shifter design. The later one used in '95 (and I believe also '94) is way more fussy and complicated.

With the switch still installed, you could test to see if it's functioning by probing into the relay socket. Pull the relay tray out as best you can for easier access. You want to look for momentary contact when the switch is depressed, testing between socket pin 1 (relay pin 15) and pin 4 (86). Meter probes often can't make good pin contact so insert short lengths of bare ended wire or even use a paper clip. Note that pin 1 is hot 12V through fuse 11 when the ignition switch is on. Those pins come straight from the switch through an 8-pin connector on the tunnel under the ash tray area. If the relay is okay then you may well see continuity there with or without the button being depressed which would indicate a short in the switch circuit, possibly in the switch itself. Otherwise test for switch functionality when the button is firmly depressed.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Well, step "a" seems to have done the trick. At least my son will have all 4 gears to get to his summer job this year.

Brian Mee

I'm not sure what the jumper does but perhaps it just bypasses the relay. It would not be unusual for a 30 year old relay to have a cracked solder joint on the board. Reflowing the joints might restore normal function.
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Any twenty minute job is just a broken bolt away from a three day ordeal

Dear Brickdad,

Hope You're well and stay so. To remove the overdrive switch, grip the "flanges" in the switch housing and pull the switch housing straight back (towards the front seats). There's very little "slack" in the wires, which are tack-welded to the switch contacts. Use white-out to mark one (of the two) wires and the corresponding contact. Then - using a small, pointed nippers - cut the wires as close as possible to the switch contacts, without damaging the switch contacts.

To replace the switch, solder the wires to the contacts.

Hope this helps.

Spook