Hello friends,
My overdrive won't advance to 4th gear. - Automatic Transmission.
I have no dash arrow (overdrive) light - ever. Not when key is in position 2 (before cranking) not when I push my shifter button to engage overdrive. - The bulb is good. It works in the other dash positions.

When I push the overdrive shifter button - the relay clicks. I have a spare and that one behaves the same.

I just replaced the solenoid with a used one with resistance of 13ohms.

Something's not talking to something else.

What would cause the Relay to respond to my shifter button - but the dash light to NEVER illuminate?

Thanks for your expertise.

The bulb could be burned out, which would be the simple explanation, or there could be a worn-through wire to the solenoid on the transmission. As far as I know, the solenoid always has power, unless the OD switch turns off the power.

Maybe someone else can answer this, or has a wiring diagram handy.

Good Luck, and the quick test for the kickdown cable is simply to remove it from the throttle spool and secure it where it won't catch on anything (a simple twist tie would work fine for that. While it's disconnected, if you want to downshift, you'll have to do it manually.

I think you are confused about what overdrive is. When your overdrive system is working properly, pushing the button on the shifter locks the car out of overdrive. If you are doing more than 40mph (or therabouts) you are probably driving in 4th gear, which is an overdrive gear on the AW70 transmission. Pushing the button de-energizes the solenoid, which disengages overdrive; that means you are in 3rd gear.

Keep in mind that the relay grounds the arrow light - it is always supplied power through the cluster. Whether you have OD or not, if the relay is clicking but the arrow is not coming on, I would look first to the single wire on the back of the gauge cluster, red/yellow I believe, that connects to the lower right hand side. That should be the ground path for the OD Off light.

Awesome. I'll take a look at the ground. Thanks!

"What would cause the Relay to respond to my shifter button - but the dash light to NEVER illuminate?"
• It might be the wrong relay. The innards are rather unique (PN 3523804, White case). If the relay is correct but failing to activate, the Arrow would be lit all the time.

"I have no dash arrow (overdrive) light - ever."
• No Arrow normally means that the OD is ON (relay is OFF). The arrow (when lit) signifies a Relay ON "upshift" to OD is available.


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

I goofed as to the OD relay's state in my previous post above.
See correction below:


"I have no dash arrow (overdrive) light - ever."
• No Arrow normally means that the OD is ON (relay is ON).
When the "Up Arrow" is lit, the relay is OFF, and a relay ON "upshift" to OD is possible.

Scorron described it correctly.


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

'If the relay is correct but failing to activate, the Arrow would be lit all the time.' -

I have two relays. One that was in the car when I had access to 4th gear, and a spare. Both respond to my shifter button with an audible click; neither allow access to 4th gear, and neither illuminate the dashboard arrow light. This leads me to believe that the problem is not in the relay, rather in the wiring.


"No Arrow normally means that the OD is ON (relay is OFF). The arrow (when lit) signifies a Relay ON "upshift" to OD is available." -

Yes - I have no arrow light (ever) and cannot access 4th gear. Very odd.

(1) What is the part number of the relay?
(2) Do you own a test light? Have a map?
(3) Did the problem arise "by itself?"
--
Art Benstein near Baltimore

Ohm my God, that was bad. Watt made you tell that joke?

Yes, by map I was hoping something like the diagram in the Bentley. But this is easier to follow.

Now that you mention cardboard and electromagnets, I wonder if the wiring to the solenoid shorted to ground. That happens when the insulation falls apart on the white wire leading through the shifter box to the connector clamped to the transmission where the solenoid plugs in. If the fuse (11) was replaced with a 16A fuse it should have blown when/if you forced the relay contacts closed, but perhaps only once you got to driving and the bare wire touched the transmission housing.

But if a blue one (25A) gets put in there, some say the relay circuit board foil becomes the fuse toward the solenoid, yet the battery still completes the circuit to the relay coil so you hear the clicking of the relay, but nothing gets to the solenoid. Two relays with the same fault could result from the same cause. But if you've replaced the solenoid already, certainly you've checked out that white wire for insulation crumbling while you were down there.

Anyhow, the symptom where the yellow/red wire does not provide the lamp function doesn't fit that scenario. Like it was a distinct trouble. The ground to the relay 31 would seem OK if the relay will operate with the switch. But it should also turn on the OD-OFF lamp when the relay is disengaged.

This seems to be one of those cases where Conan Doyle's process of elimination and the use of deduction (part swapping) is not the quickest way to solve this. Quickest way would be to trace the voltage using a test light. Of course the "map" helps you know what to expect. With your test light clipped to a ground* use the probe on relay pins where the wires go into the socket. On 15 (blue/black wire) your test light should light whenever the key is on. The yellow/red (87a) and white (87) wires should act the same because the relay ties those two together internally: it should light on power up and go out on alternate button presses. And finally, the black wire (31) should not light the test light.

You have the correct relay part number, but over the years it has been made differently internally. You should do these tests before bringing a third relay into play in case the original trouble is still destroying them.





*grounds that provide a good connection to a test light's alligator clip seem to be elusive inside the 240 unless you're willing to stick your head down and peer up under the dash. I've found it just as easy to pull the auto shifter cover and use the bracket where the two front screws hold the cover, because I usually have a Phillips handy.
--
Art Benstein near Baltimore

Q: What is an electrician's favorite ice cream flavor?

A: Shock-o-lot!

Thanks Art. I will get to these tests this weekend and report any success or interesting findings.

I appreciate everyone's brains and experience here.

Hello Art. Glad to have you on the case:

1 - 3523804
2 - I can get a test-light and if 'Map' means wiring schematic I can get that too.
3 - The problem did seem to just happen. On a long drive it my OD relay stopped working. I pulled over, removed it and placed a piece of cardboard between the electromagnet connections. This seemed to work - for a while. Couldn't shift down to 3rd - but I could drive over 60mph. Perhaps a few weeks after that long drive (1600 miles) the problem started.

Hope that info is useful. Thanks for digging in.

try and experiment.

remove the solenoid (you stated you have a spare) anbd remove the inner rubber o ring.

dremel a slot between the 2 tiny holes being careful NOT to extend the slot into the outer o ring area.

replace the solenoid with ONLY the outer o ring in place.

now drive the car.

if it goes into 4th gear you're done.

unless having the arrow light and ability to downshift out of 4th matters to you leave it be.

if it does NOT go into 4th gear you have something clogged in the the transmission

is it correct to presume your kick down cable functions as it should and IS properly adjusted?

Thanks for the response. I do generally use my overdrive for hills so I'd like to be able to use it. I'll look into the Kickdown cable. Never thought of that. Thanks