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Reverse lights in neutral

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#1
tynor

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In my continuing quest to exorcise electrical gremlins from the car, I notice today that my reverse lights are on when transmission is in neutral.  Reverse lights go out when in any gear (including reverse). 

During one of the sessions in last weekend's race, I threw a P0705 ("neutral switch failure") code.  I cleared the code and it did not reoccur in the remaining sessions of the weekend - and it's not reading any codes now.  So probably unrelated.

 

Help?

 


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#2
Steve Scheifler

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Two pairs of wires on top of the trans ahead of the shifter, one is neutral switch the other reverse. Sounds like they ate mixed up. You can probably pull them down on the passenger side enough to see and check by straightening the metal tabs wrapped around them.
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#3
tynor

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Two pairs of wires on top of the trans ahead of the shifter, one is neutral switch the other reverse. Sounds like they ate mixed up. You can probably pull them down on the passenger side enough to see and check by straightening the metal tabs wrapped around them.

 

On top/drivers side of housing just ahead of the shifter I can feel 2 sensors.  The aft-most sensor is connected to the harness with a single plug.  The forward-most sensor is connected with two individual (and identical - not marked) connectors. I tried swapping those two and see no change in behavior.

 

I can't find a good diagram of the sensors.  The FSM shows 3 sensors (speed, neutral and reverse) but its too low-res to tell where they live on the housing.


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#4
callumhay

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I looked at mine (1999). The sensors are on the left, located near the top, at about 10 and 11 o'clock. Look for the drain plug and then look up, they are within a few inches of that line. One is very near the top. On the lower right near the Power plant frame is the other sensor (bolted in, I think it's the speed sensor) . The two on the left of the tranny both have green wires. One connects via 2 white connectors and the other via a single 2 wire connector. Both sensors on the left screw in and look similar size. I'm sure the answer is something is connected wrong. I don't know if it's also possible to get the sensors mixed up in the holes also. Hope this helps.

Cal

#5
Steve Scheifler

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Connectors vary a bit by generation. I think early NA are a pair of round bullets and a pair of square ones, so they can't be wrong unless somone "repaired" them at some point, which is entirely possible. There are differences on later versions and switches. Never tried putting the wrong switch in a given hole but that's a good thought. Normally open vs normally closed perhaps, I've never compared them. Hmmm... perhaps others will chime in today.
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#6
William Keeling

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Connectors vary a bit by generation. I think early NA are a pair of round bullets and a pair of square ones, so they can't be wrong unless somone "repaired" them at some point, which is entirely possible. There are differences on later versions and switches. Never tried putting the wrong switch in a given hole but that's a good thought. Normally open vs normally closed perhaps, I've never compared them. Hmmm... perhaps others will chime in today.

or the switch are install backwards 


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#7
davew

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You have the switches in the wrong holes. One is normally open and one is normally closed. Unplug the switch, use a 24mm or 15/16" wrench to unscrew from the trans. Inspect the threads, one is slightly longer than the other one and you may have damaged the switch body.

 

On an NB car, the switch with the SINGLE plastic connector goes to the upper hole.

 

On an NA, the long wire goes on the top. The short wire switch should have green wires. The original design used a red wire. The updated switch( green wire) is to help the "stuck in reverse" problem on 1.6 transmissions.

 

On VVT cars you must plug in all the switches, I don't know what the actual wireing issue is, but unplugging the switches costs horsepower. 90-2000 can unplug the switches.

 

Dave


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#8
tynor

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You have the switches in the wrong holes. One is normally open and one is normally closed. Unplug the switch, use a 24mm or 15/16" wrench to unscrew from the trans. Inspect the threads, one is slightly longer than the other one and you may have damaged the switch body.

 

On an NB car, the switch with the SINGLE plastic connector goes to the upper hole.

 

 

I was able to get back under the car this weekend and... still no joy.   The switch with two separate wires is in what I'd call the "lower" sensor (that is forward).  Dave says the one with the single connector is the the "upper" one -- which is how it appears to be connected to me (see annotated pics for which connector is attached to which sensor).   I do note that the cable from the rear sensor (with the single plug) barely reaches the plug in the harness - almost as if it was intended to be in the more forward hole?)

I can't get a wrench around the upper sensor to even try a swap.  It's recessed into the housing such that it looks like you either need to get to it from above, or have some sort of slotted socket (like an O2 socket).  Open end wrench won't fit since the transmission is up against the tunnel.  My slotted O2 socket is 7/8" - and just too small to fit.   

  • Any advice on how to get at this without dropping the transmission?  
  • Can you confirm from the pics that the sensors are in the correct holes?

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Steve Tynor

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#9
Bench Racer

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I have a 1990 with a 2003 transmission. Tried a 15/16 inch open end wrench, it fits. My 1990 with the 2003 transmission has plenty of room all the way around the switch that I could slot modify a 15/16 inch deep well socket for the wires and remove the switch.

 

Your transmission top seems to fit really close the bottom of the tunnel. Doesn't take all that much room for the deep well socket to fit the switch hex. If you don't have room for the socket, put a jack under the transmission to support the transmission and engine from rotating to far against the motor mounts, disconnect the drive shaft from the diff, support the drive shaft, no need to remove drive shaft from transmission, remove the PPF transmission bolts, loosen the Diff. PPF bolts and move the transmission end of the PPF sideways so the you can lower the tail end of the transmission to gain room to remove the upper switch.  Been a while since I've played with the PPF. You may need to remove one of the diff. PPF bolts. Try without removing diff. PPF bolt. 


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