Folks,

Greatly appreciate all of your comments . . .

Here's what's been tested:

With the battery connected, and the ignition "ON", the motor not running, performed a voltage test at the "overdrive toggle "switch" to see what volts are there?

When I flipped the overdrive toggle switch to "ON", there were NO volts at the overdrive switch.

A week ago I checked the "gage" (overdrive) fuse in the fuse box, and it looked good, so I did not change it out.

Removed the OD relay, and with the ignition ON, but motor not running, I did a voltage test on the C & E circuits (pink / Blk) wires) on the OD relay, and there was 11.76 Volts at both the C & E circuits, which means I am getting good voltage at that point.

But still no overdrive, or overdrive dash light.

That's interesting on your '85 that the OD & Fuel pump "relays" were reversed.

Tomorrow I'll swap out the Fuel Pump relay with the OD relay and see what that reveals.

Since I do not have lift, I am unable to get under the car and run wires directly to the OD solenoid.

All comment welcomed . . .

 

You do not have to run a wire to the solenoid, only to the relay. There is a connection on the relay that comes from the ECM. The ecm grounds out this wire to energize the relay (when all parameters are met). I do not remember exactly which wire this is, maybe someone else can remember...terminal "A" maybe? You unhook the ECM wire, and run a wire through the firewall to your switch in the console and run the other side of the switch directly to ground. This grounds the relay, energizing it and your dash light, and hopefully your OD as well. You can pry the cover off the relay, and push it in by hand to see if it works. It should at least light up the dash light.

 

Apparently you didn't read it or understand it my previous post. Here it is again...

You're not going to get a voltage reading unless the transmission parameters will allow the overdrive to engauge; coolant temperature warm, second gear. As agent stated, to test the switch, you need to disconnect the connectors and test just the swith alone and then move on from there.

In other words, overdrive light will not engauge with the ignition on and the the car in the garage. The relay is a good place to start, however, because switches are simple and rarely go out.

 

Yea, it's getting frustrating! Do you have the schematic from the '84 manual? If not here it is:


You can see that you only get power to the switch if the relay is energized and the trans is not in 1st gear, as Willie has said. The ECM energizes the relay based on engine running parameters. The OD and Fuel Pump Relay are easily confused. There really was no rhyme or reason as to there positioning from the factory. The only way to be certain is to look at the wires. The Fuel Pump Relay should have two red and one orange wire easily seen, whereas the OD relay has no red or orange wires. As the others have said, the easiest way to test the switch is to check for continuity with your DVOM set to Ohms. If you must get the light to light and check for voltage at the switch, remove the OD Relay (you should be able to identify which one it is now!), place a jumper in the Relay Socket from the Pink/Black wire to the Light Blue wire, shift the trans into second and turn the ignition to on. The switch should now activate the OD Light and you'll see voltage at the switch. You can also simulate this with the ignition off and without removing the OD Relay from the Socket by running a fused wire from the batter positive to the ALDL. The schematic shows pin F of the ALDL but I believe this is incorrect, others can verify or you can verify wire color. This will route voltage from the battery through the Normally Closed contacts of the OD Relay (assuming the Relay is good) and with the trans not in 1st, to the OD Switch. Same deal, OD Light should light and you should measure battery voltage at the Switch.

 

Folks, again thanks for your comments /. suggestions - we are making progress . . .


Ray Quayle - I too looked at the shop manual, and confirmed the wires for the Fuel Pump Relay and the OD relay, and you also confirmed the correct color scheme - I am confident that I have the correct OD Relay and not the Fuel Pump Relay.

I checked the new OD relay for continuity, and it checked out, so I am assuming the new OD "Relay" is good.

Ray, I also tested your suggestion:

If you must get the light to light and check for voltage at the switch, remove the OD Relay, place a jumper in the Relay Socket from the Pink/Black wire to the Light Blue wire, shift the trans into second and turn the ignition to on. The switch should now activate the OD Light and you'll see voltage at the switch

In my test:

If you must get the light to light and check for voltage at the switch, remove the OD Relay, place a jumper in the Relay Socket from the Pink/Black wire to the Light Blue wire, turn the ignition on, shift the trans into second.

Ray, I tested the above as the car must be in reverse to turn the car off, and remove the key. Did I screw up the test by turning the car to ON, and then shift into 2nd gear, VS shift into 2nd gear, then turn on the ignition?

All comments welcomed . ..

The overdrive light did not come on the dash, only the check engine light came on .

Your thoughts here?

 

Did you get voltage at the switch, both sides?? If you did you should get the light to come on.. Might be bad bulb or ground on the center cluster..

 

When I performed the OD console "dash light" test that Dan Quayle suggested, by placing a wire between the A (blue) and C (Pink/Black) contacts on the OD connectors that attach to the overdrive relay, then I turned the ignition ON, and shifted into 2nd gear - with the car not running.

The only light that appeared on the console dash was the "check engine" light.

Should I have started the engine?

 

No you don't start the engine, if you have power at the switch you should have the light for the OD on..

 

ccrazor.

Thanks for your comments.

Previously I tested the OD "switch" inside car on the console, again this is an 84:


With the battery disconnected:

Without removing the overdrive console switch (2) "contacts", I attached an ohm meter to the (2) contacts at the rear of the overdrive console "switch".

Then I flipped the overdrive 'switch", the ohm reading went from .000 to 000.3, then dropped to 000.2 then to 000.1

Comments please?

Comments please . . .

 

Obviously you don't seem able to follow advice or answer simple questions.. You were told how to test the switch and how to test for the light on.. Sorry but you can't help those that won't help themselves..

 

ccrazor, thanks . . .

I am not an engineer, and a junior at this site . . .

Obviously, by the simple questions I ask should give notice that I am not a wiz kid on fixing things - but I am curious and am eager to learn.

I hope I do not offend others on this site, and again "many thanks" to those who are willing to help . . .

 

Unplug the dam* connector on the switch and then test the dam* switch with the ohmmeter. Better yet, just take it to the dealer. AAARRRGGGHHH

 

Further testing at the console OD "switch".

This is what I tested:

If you must get the light to light and check for voltage at the switch

remove the OD Relay, place a jumper in the Relay Socket from the Pink/Black wire (Circuit C) to the Light Blue wire (Circuit A), turn the ignition on, shift the trans into second.

I tested the above and got 11.60 volts at the OD console "Switch" and the OD light on the dash did NOT light up, only the the "Check Engine" light.

All comments are welcomed . . .

 

Last attempt.. You have been told several times how to test the switch, so far that doesn't appear to have happened!! You say you have voltage at the switch, which wire, one or both.. If you have voltage on the dark green the light should come on.. If not either the bulb is burnt out, a bad solder joint on the center cluster, or it is missing the ground from G101, page 8A-83.. To check this ground key on, if you sit in the seat does the seat belt light come on?? If no, you need to check G101..

 

ccrazor

Thanks for hanging in there with me . . .

I have 11.6 volts on the green contact on the OD console "Switch "- sorry I did not mention it earlier, and still no Overdrive light on the dash.

Since I do not have a lift, I took the car to have the OD unit fluid checked, it was at 90%, so I had them top it off. As I have read, if you do not have sufficent oil on the OD unit, the pressure switch will not allow the OD unit to engage.

After the above, I took the car out for a spin, once the coolant got to 180*, and the in 4th gear, I hit the OD switch, and nothing no OD light or no Overdrive.

 

ccrazor,

Are you referring to the light behind the drivers head, where the seat belt recoils?

I sat in the drivers seat, doors closed, ignition ON, and NO light above the drivers seat belt recoil assembly.

I am sorry, but what's G101, page 8A-83 ?

 

OK so with you jumping power over the OD relay you got power to one side of the switch but no OD light which looks like a bad switch. Mine was bad, too. I actually took the switch apart and cleaned it out ( it was full of ..... coffee?) the switch, being where it is, is susceptable to spills.

Also, the OD pressure switch is after the OD switch inside the transmission and not shown on that colored schematic. Yes, believe it - it's not shown but it does exist. It is shown in the shop manual in the transmission section. If the OD pressure switch does not make the dash light still lights.

 

If you read his post and look at the schematic he has power on the green wire which feeds the light. The pressure switch has nothing to do with the electrics..
With power on the green you should also be operating the solenoid..
Page 8A-83 is the page in the FSM, in post 25 you refer to a shop manual?? G101 is the ground point behind the instrument panel that supplies ground to the center cluster which is where both the OD light and the seat belt light are located.. From this you may need to pull the center cluster.. As to the non shift it looks like you are either going to have to get the car in the air to check the solenoid or get someone to do it..

 

Once the OD light is lit there's power on the dk green wire #901 which goes from the manual defeat switch to ........ an electrical connector through the side of the transmission. There is a spade connector inside the transmission to a wire which has a spade connector on the other end connected to the transmission pressure switch. From the other side of the pressure switch another wire goes to the solenoid.

That pressure switch wiring is not shown on that nice colored wiring suppliment which is so good at everything else (ask me how I know). As far as that schematic goes there is no pressure switch but we all know that it does exist. I went through this whole pressure switch mystery hunt when I cleaned the coffee out of my OD defeat switch, got the light lit but still no OD. I was low on fluid. Once I got the fluid filled up it worked....... until the OD pumped the fluid up into the manual transmission through the seal which went bad.

I found two places in the shop manual which did show the pressure switch (believe me, I combed that FSM) one was a picture of the transmission and you could see the wire going to the pressure switch I think. Another was, I think in one of the diagnostic step by step charts it may have been shown in a schematic.

So, yes, I have kneeled in my driveway with that wiring suppliment and my whole console apart and just like Dr. Mcoy on Star Treck said "No, damn it Jim, we can't abandon logic. If this schematic shows no switch then there isn't one and there's no logical reason why we should not have OD right now" But there is a switch. Why is it not on the wiring suppliment? I don't know. They have to get that stuff ready probably way in advance before production and that 4+3 was sort of a compromise that happened late in the game. I can tell you one thing - my suppliment has the switch - in pencil!

 

One more thing. Those spade connectors inside the transmission can get loose, causing the OD to chatter on bumps. You can just squeeze them a little to tighten them up. I just know way more about this stupid car then I should have to......

I also think there may be 2 problems here - A bad OD light or it's ground and a bad OD defeat switch. Probably best to get the light working first and forget about getting the OD energized until then. Once the light works you know the car wants OD and it's being held out by either the pressure switch, the solenoid (bad) or their wiring.

When you got power to one side of the OD defeat switch did you try jumping out the switch to see if the light lit. Did you get the switch disconnected and test it's ohms. By the way, if something is powered you can not use the ohms feature of your meter. The circuit has to be dead to use ohms.