4+3 doesnt switch back to OD
Thread Starter
Racer
Joined: Feb 2004
Posts: 265
Likes: 1
From: Irwindale Ca
4+3 doesnt switch back to OD
Hi guys and gals. My 4+3 doesnt switch back to OD when i gas it. I press the shifter button and nothing. It seemed to fail slowly, It was working periodically. Is there a quick fix? Thanx in advance
Mike
Mike
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
When you push the button, does the light come on?
One way to test the switch, is go 110 mph. The computer should force it into overdrive, if your relay and o/d still work. You can do this on jackstands easily if you don't want to try on the highway.
2nd step, if that doesn't work, is to switch the fuel pump relay with the o/d relay (between distributor and brake booster.) This will identify if the relay is dead.
If that doesn't do it... then you have to wire 12v (with a switch of course) directly to the overdrive.
If that doesn't work.. then top off the fluid.
If that doesn't work, then you've gotta remove the pan.
One way to test the switch, is go 110 mph. The computer should force it into overdrive, if your relay and o/d still work. You can do this on jackstands easily if you don't want to try on the highway.
2nd step, if that doesn't work, is to switch the fuel pump relay with the o/d relay (between distributor and brake booster.) This will identify if the relay is dead.
If that doesn't do it... then you have to wire 12v (with a switch of course) directly to the overdrive.
If that doesn't work.. then top off the fluid.
If that doesn't work, then you've gotta remove the pan.
Last edited by CentralCoaster; Oct 22, 2005 at 03:18 AM.
Thread Starter
Racer
Joined: Feb 2004
Posts: 265
Likes: 1
From: Irwindale Ca
Thanx central. when this happens im usually turning a corner fast. It switches off the overdrive and into the low gears. When I let off the gas, it stays in the low gears. I have to stop the vehicle and restart the vehicle for the overdrive to begin to operate again. The OD light goes off when it is in low gears and when I resume driving, it turns back on... I have about 6000 miles on a OD oil change. But i will check the fluid.
Would I be able to reach 110 mph in low 4th gear? wow that sounds like some rpm. I will also switch the fuel pump relay. I think I have a couple relays lying around that might be the right part #. And the last part, wire a 12 volts to the overdrive. That sounds much easyer. I might just do that if everything else fails... Thanx for the help
Mike
Would I be able to reach 110 mph in low 4th gear? wow that sounds like some rpm. I will also switch the fuel pump relay. I think I have a couple relays lying around that might be the right part #. And the last part, wire a 12 volts to the overdrive. That sounds much easyer. I might just do that if everything else fails... Thanx for the help
Mike
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Originally Posted by madmike
woa think ive only been up to 125... interesting info
A stock 4+3 will top out in 4th/OD ~154MPH. I forget the RPM it turns then.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Yeah, the car makes more power in overdrive at 150 than in 4th. At least with the MK2.
But now I have 2 overdrives. I'll have to do my high speed testing all over again.
So.. when you said it switches off around turns... that makes it sound like the pump is sucking air. But, this will not cause the overdrive light to turn off.
But you're saying the light turns off EXACTLY the same time it drops out of overdrive right? Maybe some loose wiring. My connection at the overdrive would always work its way loose until I taped and zip tied the hell out of it.
But now I have 2 overdrives. I'll have to do my high speed testing all over again.
So.. when you said it switches off around turns... that makes it sound like the pump is sucking air. But, this will not cause the overdrive light to turn off.
But you're saying the light turns off EXACTLY the same time it drops out of overdrive right? Maybe some loose wiring. My connection at the overdrive would always work its way loose until I taped and zip tied the hell out of it.
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Thread Starter
Racer
Joined: Feb 2004
Posts: 265
Likes: 1
From: Irwindale Ca
ya it feels like the switch. After i stop the vehicle , it resets and is fine. Only when i stomp on the pedal does it switch to racing gears and doesnt fall back after letting off the gas. I will check the wiring next.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
FWIW, A bad pressure switch or solenoid or broken wires to the overdrive, or torn filter grommet (or busted overdrive) will cause the overdrive to not work, but the dash light will still come on when you operate the switch.
A bad shifter switch or bad relay, the light wont come on at all.
Shorted relay wiring will make it go haywire, maybe even catch the car on fire. You should check the wiring harness at the fuel pump and overdrive relays and put some shrink wrap on it... the insulation shrinks back due to heat/age and causes electrical shorts.
A bad shifter switch or bad relay, the light wont come on at all.
Shorted relay wiring will make it go haywire, maybe even catch the car on fire. You should check the wiring harness at the fuel pump and overdrive relays and put some shrink wrap on it... the insulation shrinks back due to heat/age and causes electrical shorts.
