My overdrive light is illuminated all the time, regardless of which gear I am in. I was under the impression that the overdrive could only be engaged in 4th gear, so why is the light on in the lower gears? When I do shift into 4th, I can feel the OD engage, even though I haven't activated it from the turn signal stalk. If I try to disengage it while in 4th from the stalk, nothing happens! If I down shift to 3rd, I am pretty sure that the OD disengages. Since the OD engaged light is illuminated, I assume that the circuit is powered. Can anyone provide a clue as to the source of my problem?

OD light stays on any time the lever is actuated regardless of your gear. This feature let's you know that overdrive is coming whether you want it or not! The light often reminds me to turn the OD off when I am accelerating from a stop and want maximum acceleration (such as it is) until "I" decide it's time for OD

Craig
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Craig 73ES

What you are describing is normal for the O/D light.

Dave,

Starting in 1970, the 1800E and then later on the 1800ES got a throw switch instead of a momentary switch and the relay is eliminated.

However, regardless of the style of switch/relay being used, the way the the O/D light is originally wired, the light will be on if the switch/relay is engaged in the O/D position even if the transmission is NOT in 4th gear.

But if still stock and it sounds like your 1800 is still wired in a stock fashion, the O/D lockout switch on the transmission only allows power to the O/D solenoid when the transmission is in 4th gear.

I have one customer that moved the wire for the O/D light to the pole on the lockout switch that gets power when the transmission is in 4th gear and the O/D is engaged.

So for his car the O/D light is on only when the overdrive is engaged.

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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

Planetman, So what you are saying is that :
1.My overdrive lockout switch is functioning normally.
2.1972 P1800’s with M41 overdrive are wired to illuminate the OD engaged light whenever the switch/relay is energized, regardless of what gear the car is in.
3.If I reconfigure my wiring to so that the OD light gets its power from the lockout switch, it won’t illuminate unless the lockout switch is activated and the OD is positively engaged.
4.Since I cannot disengage my overdrive using the column stalk, are you suggesting that my switch/relay is the culprit? Or might it be the turn signal stalk?

Does the overdrive switch at the column move up and down and stay in either position when left alone or is just flopping?

The switch is supposed to have 2 positions, up for O/D off and down for O/D on.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

Discovered my problem. It was my ignorance of system's operation. I thought it was the same as my previus converted 544 with M41 OD in which the OD was activated using the column turn signal stalk in the fore & aft position. I now discovered that you use the right column stalk and now everything works fine.

I don't recall the specifics of the 1800E set up but I'll hazard a guess. The momentary switch in the 1800E signals a relay which in turn sends current to the lock-out switch and then forward to the solenoid. The relay also sends current to the OD lamp. Your lock-out switch and solenoid seem to be operating as intended. You likely have a non-working momentary switch which has left the relay stuck in the ON mode---or a short or poor connection in the relay itself. -- Dave