4 + 3 problem
Thread Starter
Instructor
Joined: Jul 2016
Posts: 166
Likes: 9
From: Melbourne Australia
4 + 3 problem
I've had a problem with my 88 couple since I bought it (3 months ago) in that the transmission would go into overdrive as soon as I shifted into second gear and would only change to direct drive by using the accelerator pedal. The button on the shift **** had no effect whatsoever.
Anyway on my way home last night I discovered that a Corvette and a wet road aren't a particularly good combination. I only put my foot down a little bit at the end of the freeway on ramp and I ended up spinning 270 degrees and went backwards into an embankment.
Not much damage, just pushed the right hand exhaust pipe forward a bit and clogged it with dirt. Funny thing is, now my car always stays in direct drive and nothing will get it to go into overdrive.
All suggestions are welcome.
Anyway on my way home last night I discovered that a Corvette and a wet road aren't a particularly good combination. I only put my foot down a little bit at the end of the freeway on ramp and I ended up spinning 270 degrees and went backwards into an embankment.
Not much damage, just pushed the right hand exhaust pipe forward a bit and clogged it with dirt. Funny thing is, now my car always stays in direct drive and nothing will get it to go into overdrive.
All suggestions are welcome.
Melting Slicks
Joined: Mar 2016
Posts: 2,778
Likes: 580
From: Langley BC
Glad to here you were not injured in the crash, spinning out at freeway speeds into an embankment sounds very scary.
You stated that the shifter button has 'no effect' on the O.D When you press the button does it turn the OD light on the dash on/off?
You stated that the shifter button has 'no effect' on the O.D When you press the button does it turn the OD light on the dash on/off?
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
It's possible that the button on the shifter is not allowing the OD switch to turn ON/OFF. My '87 had the same issue but it just took 3-4 tries with the button to get the OD to stop working. I think this is sort of a common problem as the button gets lots of use and simply wears out. The button operates a momentary contact switch and it would be possible to get a similar switch and mount it on the console and run the two wires from the shifter to a new switch. You would have to take your hand off the shifter when using the OD manually.
The default for the OD is ON so to effectively disengage the OD is the switch. But the OD can be turned OFF by depressing the gas pedal about 60% while in 1st. This will keep the OD from working until you shift into 4th gear, or turning the ignition to OFF.
Here's a page that shows how the 4+3 works.
The default for the OD is ON so to effectively disengage the OD is the switch. But the OD can be turned OFF by depressing the gas pedal about 60% while in 1st. This will keep the OD from working until you shift into 4th gear, or turning the ignition to OFF.
Here's a page that shows how the 4+3 works.
Thread Starter
Instructor
Joined: Jul 2016
Posts: 166
Likes: 9
From: Melbourne Australia
The OD light doesn't come on at all, and can someone tell me where the switch is actually located?
Melting Slicks
Joined: Mar 2016
Posts: 2,778
Likes: 580
From: Langley BC
I wasn't doing highway speed at the time. The on ramp was actually a tight loop and I had just gotten to the straight section doing perhaps 30 mph in second gear and overdrive and gave it a bit of gas when the back of the car spun out. It was so quick I didn't have a chance to do anything about it other than hit the brakes and hope there wasn't anything solid behind me, but it was scary as I didn't give it much gas at all.
The OD light doesn't come on at all, and can someone tell me where the switch is actually located?
The OD light doesn't come on at all, and can someone tell me where the switch is actually located?
So my guess is it is either a switch or the relay that has gone bad.
You asked where the O.D switch is... it is on the shifter in 88's. I haven't taken my shifter apart before so I can't tell you exactly how to change the switch off hand, but I would think the FSM (factory service manual) will have a diagram of it and/or the procedure to replace it. If you don't have a FSM I can look in mine and try to find a diagram for you....just let me know.
I think corvette central and other aftermarket suppliers sell replacement O.D switches.
Last edited by DMITTZ; Apr 11, 2017 at 10:16 AM.
