1986 4+3 OD Problem
Thread Starter
Racer
Joined: Jul 2001
Posts: 253
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1986 4+3 OD Problem
This is a weird one and I can't search the 'recent' or 'archives' because 4+3 and "4+3" doesn't work.... :confused:
Anyway, I'm driving around town and using the OD button and all of a sudden it doesn't want to work while the trans is in gear. I can turn the OD on and off if I slip the gear shifter into neutral. So I don't think it's the switch. What's up with this thing?
This additional piece might be related - Why does OD work in first gear? Here's what happens... I'll start out from a stop in first. I'll get it up to about 20 mph and then need to coast to a stop, pushing in the clutch and leaving the shifter in 1st: the OD light comes on. I've even 'driven' in 1st OD for a couple feet - then the OD unit realizes it shouldn't be there and it pops back into 1st non-OD.
Is this normal? Or is mine really a 4+4? :rolleyes:
Anyway, I'm driving around town and using the OD button and all of a sudden it doesn't want to work while the trans is in gear. I can turn the OD on and off if I slip the gear shifter into neutral. So I don't think it's the switch. What's up with this thing?
This additional piece might be related - Why does OD work in first gear? Here's what happens... I'll start out from a stop in first. I'll get it up to about 20 mph and then need to coast to a stop, pushing in the clutch and leaving the shifter in 1st: the OD light comes on. I've even 'driven' in 1st OD for a couple feet - then the OD unit realizes it shouldn't be there and it pops back into 1st non-OD.
Is this normal? Or is mine really a 4+4? :rolleyes:
Team Owner
Joined: Mar 2000
Posts: 83,384
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From: Boston, MA
Re: 1986 4+3 OD Problem (86VetteBill)
OD in 1st is not uncommon in some situations, it was designed that way.
As for OD not working, what do you mean it works if you put the shifter in neutral. Does the switch on the shifter then work, but not if it is in gear? Or does the computer put it into OD if the shifter is in neutral and the RPM come down?
As for OD not working, what do you mean it works if you put the shifter in neutral. Does the switch on the shifter then work, but not if it is in gear? Or does the computer put it into OD if the shifter is in neutral and the RPM come down?
Team Owner
Joined: Mar 2001
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From: Cincinnati, Oh USA
Re: 1986 4+3 OD Problem (86VetteBill)
The OD switch has no control in 1st gear and the OD should not engage in first. It sounds to me its time for an OD rebuild. Last summer, my 87 was stuck in OD and shifted in even in 1st at about 15 mph. Call SK speed at 631 957 9427 and describe your problem.
Team Owner
Joined: Mar 2000
Posts: 83,384
Likes: 88
From: Boston, MA
Re: 1986 4+3 OD Problem (jfb)
The OD switch has no control in 1st gear and the OD should not engage in first.
Racer
Joined: Mar 2001
Posts: 269
Likes: 1
From: woodstock, Ga
Re: 1986 4+3 OD Problem (86VetteBill)
the gearzone has a chart on what units had what, it sounds like under certain conditions you can have OD in first, especially after a downshift to first while in OD..
Team Owner
Joined: Mar 2000
Posts: 83,384
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From: Boston, MA
Re: 1986 4+3 OD Problem (frank moran)
....especially after a downshift to first while in OD..
This was to prevent a "clunking" sensation when slowing to a stop sign. The overdrive would not shift out until you reached (I think) 1 mph.
Team Owner
Joined: May 2002
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Re: 1986 4+3 OD Problem (86VetteBill)
Thread Starter
Racer
Joined: Jul 2001
Posts: 253
Likes: 0
Re: 1986 4+3 OD Problem (scorp508)
Maybe an example will work better...
From a stand-still with the OD turned off - meaning the OD won't engage while I drive through the gears. I take off - 1st, 2nd, 3rd, and now into 4th gear. I'm doing 35mph. I press the OD button on the top of my shifter. Nothing happens. I slide the shifter into neutral and press the button. The OD engages. I slip the shifter into 4th (or 3rd or 2nd for that matter) and I'm driving with the OD engaged.
What's happening?
From a stand-still with the OD turned off - meaning the OD won't engage while I drive through the gears. I take off - 1st, 2nd, 3rd, and now into 4th gear. I'm doing 35mph. I press the OD button on the top of my shifter. Nothing happens. I slide the shifter into neutral and press the button. The OD engages. I slip the shifter into 4th (or 3rd or 2nd for that matter) and I'm driving with the OD engaged.
What's happening?
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Melting Slicks
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From: Construction Sucks! MI
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St. Jude Contributor '03 & '05
Re: 1986 4+3 OD Problem (86VetteBill)
i had a smiliar problem, but the button wouldn't work at all. mine ended up being an electrical problem. the two wires that connect to the button inside the console had become lose. the soldering had broke. right before it happened, i would work and then not work until it completely pulled lose. i would check the connection of these two wires. unscrew the console, follow the skinny little rod the runs from the top of the shifter to this button. i bought a pair of clips from the local hardware store for about 50 cents a piece and reattached them. sorry for the non-technical use of words.
Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Re: 1986 4+3 OD Problem (86VetteBill)
Strange. I would think if it was the momentary switch, it wouldn't depend on if you're in gear or not. Seems like the OD won't turn on if there's any load on it.
I'm guessing the computer relies on the three (?) ball switchs (1-2, 3-4, R), the TPS, the coolant temp sensor, and engine speed to determine whether the OD can activate or not.
I'm guessing the computer relies on the three (?) ball switchs (1-2, 3-4, R), the TPS, the coolant temp sensor, and engine speed to determine whether the OD can activate or not.
Thread Starter
Racer
Joined: Jul 2001
Posts: 253
Likes: 0
Re: 1986 4+3 OD Problem (scorp508)
A few of you were pretty close when you suggested that I check the wiring. It was a break in the wire where the zip tie holds the wire to the shifter. I think the zip tie was way too tight.
Anyway, that explains why the OD button would only work in certain gear positions.
Thanks for the input!
Anyway, that explains why the OD button would only work in certain gear positions.
Thanks for the input!
Thread Starter
Racer
Joined: Jul 2001
Posts: 253
Likes: 0
Re: 1986 4+3 OD Problem (scorp508)
Hey Scorp - I'm not sure what you're asking about 'reset'. The wires were sometimes 'contact' and sometimes 'no contact' depending on where the shifter was.
The OD always reset to 'normal' when I started the car. But sometimes I need to turn it off, which became more difficult as the 'no-contact' situation happened more often.
The OD always reset to 'normal' when I started the car. But sometimes I need to turn it off, which became more difficult as the 'no-contact' situation happened more often.
Melting Slicks
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From: Construction Sucks! MI
Cruise-In V Veteran
St. Jude Contributor '03 & '05
Re: 1986 4+3 OD Problem (86VetteBill)
[QUOTE]I think the zip tie was way too tight.QUOTE]
I noticed that also when I fixed mine, so I losened them a bit. They may have been the reason the soldering had failed on mine.
I noticed that also when I fixed mine, so I losened them a bit. They may have been the reason the soldering had failed on mine.
