No 3rd gear unless fuse #13 is pulled

[RamblinDMC]

Hey everyone,

My doesn't seem to want to shift into 3rd. It shifts fine from 1st to 2nd at around 4000 rpm, seems a little high??? It will shift into 3rd fine if I pull fuse #13, if I put it back in, it shifts back into 2nd immediately. Bad shift computer?

[DMCMW Dave]

Yes.

[Ron]

I wondering if it could be the Kick Down Switch (WOT) stuck, or its wire shorted to ground (with that high shift point (too)).
Or, possibly, the GC's 12v supply wire shorted to the one solenoid wire in its harness.

[DMCMW Dave]

I've never seen either of those issues in a real car. Seen the governor cause problem that dozens of times a year. Go with the common failure mode first. You can test it, but if is an original governor it is almost certainly Bad.

[PJ Grady Inc.]

I wondering if it could be the Kick Down Switch (WOT) stuck, or its wire shorted to ground (with that high shift point (too)).
Or, possibly, the GC's 12v supply wire shorted to the one solenoid wire in its harness.

I think Dave got it right IMHO but it can't hurt to poke around a bit.
Rob

[RamblinDMC]

I'm pretty sure the kickdown switch is working, it downshifts from 2nd to 1st if you hit the throttle. If it were shorted wouldn't it always stay in 1st?
I'll plan on getting a new shift computer. Thanks!

[AugustneverEnds]

My .02 worth: Say sayonara to the governor. If your governor is still running with the original boards, they are shot or getting closer everyday. Take it out send it to your favorite vendor for a rebuild and rest assured your transmission won't grenade thanks to a malfunctioning governor.

[David T]

My .02 worth: Say sayonara to the governor. If your governor is still running with the original boards, they are shot or getting closer everyday. Take it out send it to your favorite vendor for a rebuild and rest assured your transmission won't grenade thanks to a malfunctioning governor.

Another possibility is the wiring going to the shift computer got melted. It can cause all kinds of strange failure modes. It is worth checking the kick-down switch just in case it is stuck. If you replaced the shift computer and you still had no 3rd gear that is what you would have to do anyway.

[RamblinDMC]

Just checked the lockdown switch. It's okay. Looks like its time for a new shift governor!

[AugustneverEnds]

Just checked the lockdown switch. It's okay. Looks like its time for a new shift governor!

Not exactly. You remove the shift governor, send it to the vendor of your choice (DMC Midwest fixed mine, had it back to me in three days :thumbup2: and reinstall the same governor with new updated internal "stuff".

I used this guide to get mine out: http://dmctalk.org/showthread.php?7648-How-To-Remove-the-Automatic-Transmission-Governor-Computer&highlight=automatic+governor

Good luck it's not too bad

[Ron]

If it were shorted wouldn't it always stay in 1st?
Yes (I thought you meant it was shifting late).

I'll plan on getting a new shift computer. Thanks!
Gets my vote...You can check the harness on the qay out...

[RamblinDMC]

Yes (I thought you meant it was shifting late).

Gets my vote...You can check the harness on the qay out...
Yes it shifts late into 2nd. At around 4000 rpm

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[RamblinDMC]

Would it be worthwhile to replace every failure prone component on the GC board? Caps, transistors, resistors? I have an extensive background in vintage electronics and a repair such as this isn't really beyond my abilities. Is a repaired original board worth the effort and money savings over a new one from DMC?

[David T]

Would it be worthwhile to replace every failure prone component on the GC board? Caps, transistors, resistors? I have an extensive background in vintage electronics and a repair such as this isn't really beyond my abilities. Is a repaired original board worth the effort and money savings over a new one from DMC?

Late/erratic shifting that seems to change depending on temperature is easily fixable. Classic symptoms. Since it does eventually get in to each gear the output transistors are not damaged. There are 2 caps to replace and some cold solder joints. You will easily see the bad caps and you just reheat all of the solder joints. You do not have to replace everything.

[RamblinDMC]

Late/erratic shifting that seems to change depending on temperature is easily fixable. Classic symptoms. Since it does eventually get in to each gear the output transistors are not damaged. There are 2 caps to replace and some cold solder joints. You will easily see the bad caps and you just reheat all of the solder joints. You do not have to replace everything.

The late shifting doesn't seem to alter due to temperature. It's always at 4,000 rpm for 1st to 2nd. It never makes it to 3rd unless the fuse is pulled. Are they carbon comp resistors? Those don't take heat well.

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[Bitsyncmaster]

Would it be worthwhile to replace every failure prone component on the GC board? Caps, transistors, resistors? I have an extensive background in vintage electronics and a repair such as this isn't really beyond my abilities. Is a repaired original board worth the effort and money savings over a new one from DMC?

It's a real pain to do any soldering to the OEM circuit boards. The boards are conformal coated and you really need to remove the coating to get good solder joints. The coating even makes it hard to see broken joints. My recommendation is to buy a new replacement unit that has circuit boards with plated through holes which eliminates broken solder joints caused by repeated heating and cooling.

[David T]

It's a real pain to do any soldering to the OEM circuit boards. The boards are conformal coated and you really need to remove the coating to get good solder joints. The coating even makes it hard to see broken joints. My recommendation is to buy a new replacement unit that has circuit boards with plated through holes which eliminates broken solder joints caused by repeated heating and cooling.

Not all of the boards were coated but you're right, the ones that are coated are a real pain to clean the coating off of. Not everyone will want to spend the $$$ to replace the whole thing, some owners want to save what they can even if it means some work. Once worked on, the OEM shift computer can be dependable. There are a LOT of repaired ones out there working, for a long time there was no other choice. They don't always fail where they are temperature dependent but it IS a common symptom.

[RamblinDMC]

I'll remove it and see if the coating will make it too difficult. If I can fix it for around $10 of new components, its definitely worth a shot.

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[Bitsyncmaster]

I'll remove it and see if the coating will make it too difficult. If I can fix it for around $10 of new components, its definitely worth a shot.

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You can use solder wick to get the coating off but it's a lot of work if you need to touch up a lot of joints.

[Ron]

Yes it shifts late into 2nd. At around 4000 rpm

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Would it be worthwhile to replace every failure prone component on the GC board? Caps, transistors, resistors? I have an extensive background in vintage electronics and a repair such as this isn't really beyond my abilities. Is a repaired original board worth the effort and money savings over a new one from DMC?


When I got my D, it had one of the 2 shift solenoids energized any time the key was on, shorted by exhaust system damage. Normally, both solenoids are energized for 1st, one is dropped for 2nd, the other for 3rd. The first to be dropped had the short, so when the second dropped, it was in an undefined mode, so to speak...(toasted GC too). I was thinking if your's had a similar problem, but with the other solenoid, it would have symptoms similar to what I thought you were saying....

...

I understand the DMC unit is good. But, if you like to learn/play:
Odds are solder joints, 2 caps, 2 transistors, in that order...$20 (Never seen anything else wrong with one.)
http://dmctalk.org/showthread.php?350-Automatic-Transmission-Governor

[DMCMW Dave]

Actually the logic is:
Both energized=1st gear
one energized=2nd gear
None energized (same as far pulled) =3rd gear.


Sent from phone

[Ron]

Actually the logic is:
...:hmm:
Both energized=1st gear == "both solenoids are energized for 1st"
one energized=2nd gear == "one is dropped for 2nd"
None energized (same as far pulled)=3rd gear == "the other for 3rd"

What's the difference ???

on-on=1st gear
on-off=2nd gear
off-off=3rd gear
I had a off-on = "undefined"= toasted clutch pack

[DMCMW Dave]

:hmm:
Both energized=1st gear == "both solenoids are energized for 1st"
one energized=2nd gear == "one is dropped for 2nd"
None energized (same as far pulled)=3rd gear == "the other for 3rd"

What's the difference ???

on-on=1st gear
on-off=2nd gear
off-off=3rd gear
I had a off-on = "undefined"= toasted clutch pack


I guess I read your comment wrong, I thought you meant that second was one dropped and third was the other dropped. I.E. the illegal condition you mention.