Vehicle: Model 940, 1994 non-turbo

In the last couple of months, on occasion my 940 will indicate the 4th gear disengaged on the control panel. Indeed, the 4th gear will not engage for up to a few minutes. Then the light goes off and everything appears to work fine. No, it's not because I have inadvertantly pressed the button on the shift knob. Pressing this button does not then engage 4th. I am still collecting data to identify under which conditions this occurs. It seems that it is most likely to happen when the car has been run and then sits for a short while. However, this could be misleading data. I have never see a situation where the car wants to downshift to 3rd once it is in 4th gear but fear that this may happen some day.

Where should I look for the solution to this problem?

Best regards,
Ron

If it drops out of Overdrive—and the Upshift Arrow light comes on—the OD relay is also probably "dropping out". See control circuit summary below:

OD operation involves 5 components and the wiring that connects them...

1) Fuse 11 (200) or 12 (700/900) supplies voltage to items #2, #3, #4, and #5

2) The Shifter button/switch (turns OD relay off and on)

3) The OD relay (controls Upshift Arrow light and OD Solenoid - separate wires)

4) The Upshift Arrow light (ON means relay and OD are OFF)

5) The OD solenoid (Allows OD engagement when ON, the "default" Relay state at Key On)

If the Shifter switch makes the Arrow light (#4) go on and off, then items 1, 2, and 3 are OK, and the problem is most likely the undercar wire to the Solenoid (#5) or the wire connector terminal.

Less likely would be be Solenoid itself.
Also possible (but very unlikely) would be the relay controlling the Arrow light (#4) correctly, but failing to activate the Solenoid.
An internal transmission problem is also possible.

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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

That was a problem I had with my car...replacing the OD relay fixed it and I haven't had problems since.

Replace the OD relay ($35 or so at FCPG) behind the ashtray. You will have to remove the cubby hole to get good access to it. This is not the only cause of the problem your are having but the most likely cause.
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Tom F. Couple of Volvos Mods, RainX & cup holders.