TR2/3/3A overdrive does not function

[sp53]

My overdrive does not function, click, smoke, or engage. I never really had the OD checked out before I installed it beside taking the cover off of the Trans and checking for broken teeth. The relay was replaced and the solenoid cosmetically cleaned. The switch is an old oval switch that I took apart and cleaned and it should work. I followed the wiring diagram in the book and there is a fuse.

I am going to start trouble shooting the problem and my first thought is to take the switch out of the circuit and bypass the switch by touching the wires together and see if the relay clicks or solenoid does something. I have never owned an overdrive, so my questions are going to be out there. Anyways any help would be helpful

Steve

 

[bobhustead]

No longer an overdrive expert. My first guess is the electricity supply to the solenoid. Bypass the cutout switches on the trans top and see if you get a click.
Bob

 

[Sarastro]

You've got the overdrive switch, two cutouts, a relay, and the solenoid. The problem could be in any of them. I'd start by using an ohmmeter or continuity tester to make sure they are opening and closing as they should. You should be able to hear the relay click, so if you are getting voltage to its coil and you don't hear anything, that's probably the culprit.

 

[CJD]

I think your plan is a good starting point. The relay is loud enough to hear, so if there is no click, then make sure the switch is energizing all the way to the relay. a test light or voltmeter will be your best friend for this testing.

 

[sp53]

I looked deeper into the problem with my OD not working. The way the OD wiring harness sits in my car, I found it easier to pull the carpet to get a clear look. I have power at C1 so the hot from the ignition to C1 is good. The Switch seems to be stuck closed. I took an OHM meter and put that across the 2 ends of the wires that come out of the switch and could not get the switch to open to infinity, I guess—perhaps I am missed something.

Anyways, I have another switch that is not the tear drop type. It is a Lucas switch that is spring loaded and goes back to off. I do not know how heavy of switch is required for an OD. I figure OD switches are high amperage because they look beefy. I took a picture and it just might be an OD switch, but I think it looks small.

Steve

 

[CJD]

Since it goes through the relay, I don't think the switch sees more than 1/2 amp at most. The relay to the OD solenoid has to take 10 amps for a short time, and 1 amp continuous.

 

[KVH]

My overdrive does not function, click, smoke, or engage. I never really had the OD checked out before I installed it beside taking the cover off of the Trans and checking for broken teeth. The relay was replaced and the solenoid cosmetically cleaned. The switch is an old oval switch that I took apart and cleaned and it should work. I followed the wiring diagram in the book and there is a fuse.

I am going to start trouble shooting the problem and my first thought is to take the switch out of the circuit and bypass the switch by touching the wires together and see if the relay clicks or solenoid does something. I have never owned an overdrive, so my questions are going to be out there. Anyways any help would be helpful

Steve

Fixed yet? Right or wrong, I always assume the problem is "other than" the relays and switches. I first assume the problem is "me." If you're getting nothing at all, I'd check the wiring to your switch, including the quality of your connections. I was shocked last week upon discovering that a seemingly good spade connector was corroded and negating all function. If that wiring is good, try bypassing the switch to see what happens. If still nothing, I'd check the negative ground wires that lead to each overdrive switch on the transmission cover. Next, I'd verify that your solenoid wiring is correct and that your solenoid is good. I had the lead wire from the solenoid pull out of the bullet connector in the main OD wiring harness. That surprised me, too. I'd only checked that 3 times.

I assume you have your wiring diagram out, and you've verified all wire colors are correct?

Think simple. It usually is. If not already fixed, here's another question. Is your relay switch one of those that require a jumper? Remember that discussion from the horn thread? Nothing would ever have alerted me to that issue if it weren't for a thread right here. For the horn relay, you must jump W-2 to C-2. Nowhere in the instructions, but all right here from those who knew.

 

[Popeye]

If your switch appears stuck closed, I would isolate it and test it.

If you were getting zero resistance through the switch as it is installed, it suggests either the switch is stuck closed, or a short to ground on both sides of the switch. Taking the switch out and measuring will diagnose which it is. (I would expect a switch to fail open, especially if you can still move it - but who knows?)

Also, if I understand correctly, the spare Lucas switch would only momentarily activate the solenoid. Good for debugging, but maybe not the best for use.

Do you have access to a 12v power supply to test the solenoid? You can use the car battery, but something like a battery charger might be more convenient

Good luck!

 

[sp53]

I did a lot of wiggling of wires and testing connections and did re- soldered one connection. Today I will remove the switch from the car and take it apart to see what I can see and then try the other switch.

So an OD switch is nothing special? I remember when I took apart the stock switch there was a rolling type connection that seemed to move to another space or connection in the switch. I figured the switch was a simple-- on off--- switch that did not stay connected and returned back to off when let go. Is that correct? Or are the switches mystical.

My horn does not have a relay and I do not remember bypassing a relay. I can easily jumper W2 and C2. If I did that what can I expect to happen? I guess the only thing I found out was the fuse is good to C1 so there is power to the relay and that I do not fit under the dash well.

Steve

 

[PAUL161]

Don't know about TR ODs but I had that problem on my 72 MGB and it was the solenoid sticking. Took it out and cleaned it and has worked perfectly ever since. PJ

 

[Popeye]

The solenoid jumpering: for a “normal” wiring harness this should not be necessary for the OD relay. The horn relay originally was a three post type, most present-day relays have four connectors. As such, a jumper is needed there. Basically, the relay needs power to one side each of the load (C1/C2) and the actuating circuits (W1/W2). The combination of one of the lockout switches on the transmission plus the OD switch on the dash connect the “W” side to ground; this connection in turn closes the “C” side and activates the solenoid.

It is a bit hard to tell from the photos, but it looks like your solenoid has four wires coming to it.

The OD switch on the dashboard is like a light switch: on or off. When switched “on” the relay clicks closed (high current), followed by a low current “holding” of the relay in position. The switch itself does not see a lot of current.

 

[CJD]

Funny, Steve!

Yes, the switch is just a heavy duty on/off switch...normally off. It completes the circuit to the relay. The shifter switch is either a single switch on the 3/4 shifter (old style for 4th gear only operation), or a double switch that also includes 1/2nd gear (later style for 2/3/4 gear operation).

So, here is a quick walk through the wiring to the OD...assuming it is as original, of course, and what they should read with a test lamp (note: hot means 12 v, grounded means 0 ohms to chassis ground, and cold means neither 12v or 0 ohms to ground):

1 Hot wire from A3 fuse, normally tapped at the start switch goes to the W1 post on the relay...white wire. ( always hot when ignition on, cold when ign off)
2 From the W2 post on the relay a yellow/green wire goes to the OD dash switch...either post (always hot with ignition on).
3 From the other post on the OD dash switch, a black to the tunnel, then yellow through the tunnel goes to the shift switch or switches (hot when ignition and OD dash switch are on...cold when switch is off and tranny is in Neut or Rev. Grounded if shifter switches are in proper gear).
4 The second post on one or both shift switch(es) is normally grounded with an eyelet to one of the shifter cover bolts...black wire(s). (always grounded)

That completes the low amperage circuit.

For the solenoid side of the circuit, the wiring should go:

1 Power taps with a brown/white wire to the control box or the ammeter load side, and runs to the C1 post on the relay (always hot).
2 From the C2 post of the relay, a pink/yellow wire goes to the solenoid (normally cold...hot when all OD switches and ignition switch are set properly).
3 A second black solenoid wire runs to ground (always grounded).

Other points: There should be a bullet connector somewhere near the grommet where the 2 wires (yellow/green and yellow/pink) enter the tranny tunnel, in order to allow you to remove the tunnel cover.

This should get your wiring checked up to the solenoid. Just use a test light and check each wire above when cycling the appropriate switch(es). The solenoid is another story in itself!

 

[sp53]

Went back at it for a while and found out that the original switch I rebuild has a problem. The poles are not making contact. I must have looked at it wrong when I rebuilt it, and did not see the brass piece that sides back and forth does not close and open the circuit, perhaps there is a piece missing or some anybody know please speak up.

I took a picture of the other switch that might work. I am actually uncertain if the power needs to stay on at the relay or what? Does the switch supply power just for a few seconds? Does the relay get involved after the initial power has been removed? I see there a 2 power supplies, so if anyone can explain or understand what I think I see I would appreciate it

I took the 2 leads that I had the switch on and just touched them together and the relay clicked. So I put a remote start switch in the circuit and looped it over the passenger dash handle and was maybe going for a test drive.

Hate to sound dumb, but at what speed and when should I engage the relay, say 25 mph in second gear? Should I push in the clutch?

steve

 

[KVH]

That's a good speed for second, but maybe go a bit faster, and yes no problem using clutch. Some say don't bother, but I like a nice smooth transition. The bump bothers me. I always think a bearing is being hit too hard. Is yours a Type A, Laycock?

 

[Popeye]

The OD switch supplies power as long as the OD is engaged. The current is quite low, as the solenoid has a lot of resistance.

(V=IR; “R” is big, V is fixed at 12 volts, so the resulting current, I, is small. … I’m a mechanical guy, this is about the limit of my electronic knowledge!)

 

[sp53]

i did not see that people had posted before i post sorry my brain was fried. The OD came stock in a 1961 tr3. i think that means a type, but not sure.

 

[sp53]

Ok I think I am seeing things a little clearer. The remote start is not going to work because it does not stay on and there is a chance my other switch will work if the switch stays closed. Has anyone taken apart an original switch? They are interesting inside with a spring in the middle between two poles with a brass plate that slides back and forth between the poles. I just cannot see how to make mine work. It is like the switch needs a 3rd wire or something. I really would like to fix this one.

Sounds like I need to get a new switch before I can do much testing. I could use a house hood light switch to see if the solenoid does its job and I guess there is an adjustment on the solenoid also; heck i am not sure if it works yet. I appreciate all the help, I think there is smoke coming out my ears.



steve

 

[Popeye]

As long as the smoke is coming out of the ears, and not the wires, you might be ok

Good luck!

 

[CJD]

In answer to your switch question...the switch must stay closed the entire time the OD is operating. The relay does not "hold" anything longer than the switch position tells it to.

 

[KVH]

Funny, Steve!

Yes, the switch is just a heavy duty on/off switch...normally off. It completes the circuit to the relay. The shifter switch is either a single switch on the 3/4 shifter (old style for 4th gear only operation), or a double switch that also includes 1/2nd gear (later style for 2/3/4 gear operation).

So, here is a quick walk through the wiring to the OD...assuming it is as original, of course, and what they should read with a test lamp (note: hot means 12 v, grounded means 0 ohms to chassis ground, and cold means neither 12v or 0 ohms to ground):

1 Hot wire from A3 fuse, normally tapped at the start switch goes to the W1 post on the relay...white wire. ( always hot when ignition on, cold when ign off)
2 From the W2 post on the relay a yellow/green wire goes to the OD dash switch...either post (always hot with ignition on).
3 From the other post on the OD dash switch, a black to the tunnel, then yellow through the tunnel goes to the shift switch or switches (hot when ignition and OD dash switch are on...cold when switch is off and tranny is in Neut or Rev. Grounded if shifter switches are in proper gear).
4 The second post on one or both shift switch(es) is normally grounded with an eyelet to one of the shifter cover bolts...black wire(s). (always grounded)

That completes the low amperage circuit.

For the solenoid side of the circuit, the wiring should go:

1 Power taps with a brown/white wire to the control box or the ammeter load side, and runs to the C1 post on the relay (always hot).
2 From the C2 post of the relay, a pink/yellow wire goes to the solenoid (normally cold...hot when all OD switches and ignition switch are set properly).
3 A second black solenoid wire runs to ground (always grounded).

Other points: There should be a bullet connector somewhere near the grommet where the 2 wires (yellow/green and yellow/pink) enter the tranny tunnel, in order to allow you to remove the tunnel cover.

This should get your wiring checked up to the solenoid. Just use a test light and check each wire above when cycling the appropriate switch(es). The solenoid is another story in itself!

THAT'S ONE GREAT POST!! Thanks for that summary, I’m going to bookmark or tag it somehow, because it won’t be long before I need it again. I once crossed the yellow with the yellow/pink. If I do that again, I’ll look hard in the mirror, knowing it’s time to put my cars and tools on Craigslist.