4 + 3 problems .. help!

[corvetteDan]

Well, there I was driving down the freeway after a wash and wax job, then without warning the old 4+3 starts jumping from high range to low range... I just came back from a 2000 road trip, Before I went I had the trans filter changed and the fluid level checked... now this.. And to make it all the more strange it stopped doing it all together about 4 miles later.
I've been looking into the Tremeck replacement, but that is some 3200 clams, I hate to put more money into the old 4 +3 when I don't want to get another.... ( Katrina cost all my car funds with home damage - darn it!)
As a side note,... when the trans game me trouble I had been reving in low range powering up the onramp as I often do.. then shift into high three when my speed is up... wonder if the trans is shot, low again on fluid, or just one of those things. problem is, now I cannot trust the car on any more long trips until this is put to rest.

Any ideas? Past issues of the same type?

Dan

 

[JonM]

I don't have an 88 with this button on the stick...but do a search. If I recall, the switch and wires become useless and do what you are describing. You need to dismantal it and take a look at the wires.

SWITCH LINK

A few other things it could be is...

1. Insufficient Lubricant...make sure its not leaking out slowly
2. Make sure the speedo is working
3. Make sure the Temp Gage is working correctly
4. Check for 12 volts at the 1st gear switch on the side cover
5. Check for 12 volts @ the solenoid (engine at OT, wheels off the ground, shift from first to second-solenoid should energize.
6. Check the solenoid check ball

Hope this helps a little...but check the switch and wires first

 

[WhalePirot]

Don't freak......yet

I am very familiar with the 4+3. The logic for the '88 is simplified from the early models, but my '87 manual states this logic . You might check the owner's manual normal O/D operation, if you are not positive about it.

There are many reasons for what you've experienced:
- it might have been 'on it' too hard in 3rd for O/D,
- it might be low on fluid, or just had a bubble to eliminate, after the fluid change,
- the on/off console switch may be failing,
- there are more possibilities.

Does it act normally in 4th gear? It is supposed to come on above 110mph and switch off with hard acceleration, then reengage (only in 4th) with less acceleration.

O/D is only operational when the ECM is in closed loop. Mine cycled repeatedly, once upon a time, because my plugs wires were failing.

Spend some time driving it and see if the problem was temporary or ongoing before you freak on it. My condolences on the Katrina impact.
mike

 

[nyernga]

I am very familiar with the 4+3. The logic for the '88 is simplified from the early models, but my '87 manual states this logic . You might check the owner's manual normal O/D operation, if you are not positive about it.

There are many reasons for what you've experienced:
- it might have been 'on it' too hard in 3rd for O/D,
- it might be low on fluid, or just had a bubble to eliminate, after the fluid change,
- the on/off console switch may be failing,
- there are more possibilities.

Does it act normally in 4th gear? It is supposed to come on above 110mph and switch off with hard acceleration, then reengage (only in 4th) with less acceleration.

O/D is only operational when the ECM is in closed loop. Mine cycled repeatedly, once upon a time, because my plugs wires were failing.

Spend some time driving it and see if the problem was temporary or ongoing before you freak on it. My condolences on the Katrina impact.
mike

I agree with Mike on all the above. The 4+3 is misunderstood and badmouthed by many but I've had little or no trouble with mine in 5 years save the small things like the shifter switch, which, by the way is easy enough to check. If your OD dash light comes on when you depress the button then the switch is probably ok.
I've gotten in the habit of using the clutch pedal when shifting into OD. Of course I rarely use OD for anything other then highway driving. Check to see if the temps at which it acts up are consistent. Could be a bad temp sensor which makes the unit "think" it's warmer/colder then it actually is.

Len

 

[Agent 86]

Check the wiring connector at the OD relay. My insulation shrunk an inch leaving bare wires just waiting to meet each other.

 

[CAJUN C4]

Mine does the same thing..Sometimes..not alkl the time..it will jump in and out of OD...Few minutes later it's fine. Might work great for months. Question.? If my Console switch is getting bad..would the
"Overdrive Engaged" light blink?
Mine stays steady while doing this in and out thing.

I allways thought I had a bad Pressure switch or Solenoid?

 

[corvetteDan]

update

Thanks gents for the info, all good info for sure. It happend again today, seems to be going on more and more recently. I've noted the following:

Only seems to occur when reving the engine harder than normal ( going through gears upwards of 3500-4500).
Only jumps in and out of OD when in 4th.

I stopped by Hood Chevy close to home and all they would do was shake thier heads. "Nope, we don't work on those 4 + 3, and we don't hav any manuals for it". I did locate the kick down solinoid part number ( 14082729), but also found that it is no longer made by and stocked by chevy. I did locate one ( I think) at www.rockauto.com). At least they list one but I have not been able to speak with anyone there. Also found that the replacement 4 + 3 units do not come with the kick down unit. SOoooo, I doubt I'd buy another 4 + 3 unit anyway, but sure as hell not if I can't get the replacement parts to make it work.

If I find what is wrong with this one I'll be sure to post the info here. Tp me it seems that the best fix would be the tremeck replacement trans.. this brings up a question - concern. Not that these cars are a real collector's item, but years down the road do you guys suppose it would be worth more with the original style trans? Suppose the nice new Tremeck would devalue the car??

 

[CAJUN C4]

That's mine exactly.

Might try

www.gearzone.net

www.5speeds.com

Plese let me know if there's a fix.

CAJUN C4

 

[CAJUN C4]

I think a better choice would be the Richmond 6 Speed. Comes as a Kit from Jegs or Summit direct bolt in for a little over $2,800.00 (have a Special on)
P/N:836-7071626AA. (Jegs)

www.jegs.com

 

[JonM]

Dan...look for Scorp508 in the members list...he has had some dealings with the 88 4+3. I would drop him a note if I were you....direct him to this thread and see what he thinks.

 

[WhalePirot]

seems to occur when reving the engine harder than normal (going through gears upwards of 3500-4500). Only jumps in and out of OD when in 4th.??

So, what was the indicator light doing?

I stopped by Hood Chevy .....

Very few people can properly diagnose and fix these units. That has been true since 1984 and has not improved. See below for the best shop I've found.

You have gotten some good feedback, trying to help you. Are you trying to troubleshoot? The O/D is a great unit; much tougher than the tranny it is mated to.

Both the Tremec and the Richmond sixer have their issues, too.

Might try www.gearzone.net www.5speeds.com

Paul (at the above) no longer works on them. He sold all to:

http://www.skspeed.com/

I have called and talked with the transmission guysat skspeed; finding them friendly, knowledgeable and professional. They have helped me toubleshoot, understand and fix a more difficult problem with mine than you are experiencing.

 

[CAJUN C4]

Can someone list the Pro's & Con's of the various 4+3 6 speed replacements.
ZF, Tremic & Richmond.

Thanx

 

[corvetteDan]

Keisler tremec kit info

Gents, Check out http://www.keislerauto.com/gm/transmissions/corvette_84-88.asp
Keisler has this kit and after a phone call and speaking with them it seems they are very customer friendly. I too like the richmond, but this kit is sure in the running. Also, it is on sale at below 3K for the time being.

Whale Pilot, to answer your question on the indicator light. When the trans is shifting in and out of OD on its own, the OD indicator light in the dash stays on... no changes. My gut feeling is that the kick down solinod is acting up, but no real basis for this view on my part. Of note, a replacement kick down unit has yet to be located. ( got three people looking for one now). I'm leaning to the 5 or 6 speed replacement and do away with all the DN 4+3 issues all at one time........

 

[MBDiagMan]

Corvette Dan,

First check fluid by removing fill plug on the overdrive unit and checking the level.

The problem you describe could very likely be the spade connector at the transmission simply being loose. Been there, done that. Check that connection first and make sure that it is secure. If necessary remove the connector and tighten the wings on the connector slightly with a pair of pliers.

If that doesn't work, turn on the ignition and then press the button on the stick once, then measure the voltage at the wire that goes to the transmission with it removed from the transmission. If it has voltage then the problem is most likely the coil in the transmission which is easily replaced. Check it with an ohmmeter first. If the coil is open, replace it.

If you do NOT have voltage at the wire, run down the circuit checking the relay and the switch at the bottom of the stick.

I'm sorry, but as far as I'm concerned any tech who shrugs his shoulders and says that he does not understand the 4+3 should be avoided and he should find another line of work. It is a very simple circuit to follow. These are the idiots that have given the 4+3 a very undeserved bad reputation.

I have factory service manuals and wiring diagrams if you need copies.

Good luck,

 

[nyernga]

Corvette Dan,




I'm sorry, but as far as I'm concerned any tech who shrugs his shoulders and says that he does not understand the 4+3 should be avoided and he should find another line of work. It is a very simple circuit to follow. These are the idiots that have given the 4+3 a very undeserved bad reputation.


,

AMEN.............but the biggest issue now with the doug nash is parts availability. Good luck finding an OEM shifter switch. I had to buy a complete shifter assembly several years ago because the button was no longer available. And the assembly I bought was the last on in stock at the Corvette parts supplier here in Georgia....

Len

 

[SoLow]

AMEN.............but the biggest issue now with the doug nash is parts availability. Good luck finding an OEM shifter switch. I had to buy a complete shifter assembly several years ago because the button was no longer available. And the assembly I bought was the last on in stock at the Corvette parts supplier here in Georgia....

Len

I bought one also just for the button......$395.00 for a button! If some one knows thermomoulding plastic...give me a call.........We could be rich I tell ya.........:W

By the way .......I have an extra perfect switch.........

 

[MBDiagMan]

Are you just talking about the switch that is at the bottom of the handle for the overdrive? If so, that is just a simple, little micro switch. I replaced mine about 5 or 6 years ago and I did not get it at the Chevy house. I don't remember exactly where I got it, but it was somewhere like Watson Electronics. It is an electronic part.

If you are talking about the plastic button at the top of the shifter, I believe I would fabricate something before laying out $395.

Good luck,
Doc

 

[nyernga]

By the way .......I have an extra perfect switch.........

I'd hang onto that little gem. It's the Corvette equivilant of the Hope diamond.......

 

[nyernga]

Are you just talking about the switch that is at the bottom of the handle for the overdrive?

Thats the switch. Since my replacement I've read about a replacement type switch from the place you mentioned. knock on wood mine functions fine..........

 

[WhalePirot]

When the trans is shifting in and out of OD on its own, the OD indicator light in the dash stays on

SO, the solenoid is working. It is not a 'kickdown' but is the solenoid that en/disen-gages the O/D. I understand why you call it a kickdown, though. That's how it feels.

Sounds like a hydraulic (oil pressure) problem, possibly due to low fluid, or an issue with the elecrical signal getting to the dash light and, perhaps the trany case, but not in to the internal solenoid. Either is testable, with the info provided here, w/o major effort.

I hope, by now, you have talked with the L.I. experts for this unit. mike