Need to repair, and or replace the reverse light switch. Before I go crawling under the car I was looking for more detail on the exact location of the switch.

I found a great DIY post with pictures on Renntech that is for a 996. Is the location of the switch on the 993 in the same location?

 

It's on the passenger side, about halfway up the transmission case. It's oriented differently too, it points straight out toward the passenger door. It's easy to find, it's the only sensor connection on that side of the case. My connection is seeping, so planned on installing a new o-ring on it (or just replacing the sensor) when I do tranny oil change next winter.

I'll have to check the removal... don't think a snap ring is involved like the 996 shows. But it could be that I wasn't looking hard enough at the connection.

 

It is as Jeff stated on the passenger side. Pull the rubber boot off the connector and the the 2 wires have bullet type plugs. You can pull them straight out with a pair of needle nose pliers. Unscrew the switch. You can check the switch operation with an ohm meter to make sure that is the problem.
(photo courtesy of nsully thread)

 

I found that thoroughly cleaning the switch internals after removing it from the tranny case was all it needed. reverse lights still work a few years later...

 

Thanks Jeff and Stace. Great pictures Darin... looks like a breeze.

 

Resuscitating an older thread. I have a problem with the backup lights working intermittently. The other lights on the same circuit (fog lamps) work fine and when I short the connectors at the switch the backup lights work, so the likely culprit in my case is the switch. Given its current price (> $70), I want to see whether it can be repaired / reconditioned.

I have not removed the switch yet and have a couple of questions:

1. if I remove the switch will I lose transmission fluid? The switch seems to be mounted at about the same height as the fill plug; I am assuming minimal if any fluid loss.
2. What specifically did you clean? Just the portion exposed to the gearbox internals or did you further disassemble the switch?

TIA.

/alex

 

Hi - removing the switch did not result in any fluid loss. I did have the car raised on jack stands with the passenger side slightly higher. I also did not disassemble the switch. I flooded the inside of the switch with brake cleaner and then a squirt of wd-40. The tranny pushes a spring loaded plate against the electrical contacts. That just gets gummed up. Good luck.

 

+993. During an oil change I removed my sensor. Cleaned it as referenced above. Reinstalled and back up lights functioned perfectly. I highly recommend cleaning the switch before spending the money on a replacment.

 

Stace, Mark,

thanks for the replies. I will try this the next time I have the car up.

/alex

 

I did the same clean and replace. It worked for a couple weeks and it is dead again. I may just break down and get a new switch.

 

If my reverse lights dont work should I try this?

 

Yes. The switch is usually the culprit.

 

Be careful removing the bullet (male) leads. I had one that must have been abused as it broke off at the crimp while getting the boot off. Had to re-solder it together. Not fun on your back.

 

Just spent a few hours today trying to figure out my switch woes. I have had non-functioning backup lights for months now. I'm on my 2nd or 3rd replacement at this point (over the last 3-4 years). I have been monkeying with substituting crush washer thickness to fine tune the depth the switch inserts into tranny case. I was thinking maybe the pin was worn or I didn't have the depth right....

Anyway, I shorted the bullet pins and found the lights do come on so its the switch. Like the previous poster, I cleaned the switch in the past but it was a temporary fix. I do get tranny fluid - a few drops - whenever I take the switch out so I know fluid is getting to the switch and probably gumming everything up.

Today I hooked up my DMM across the bullet connectors and found that the voltage drop was minimal while in reverse indicating that resistance of my switch doesn't go (close) to zero like its supposed to... I verified that with resistance measurement with ignition off. If I repeat the same test by shifting the tranny in and out of reverse, the resistance is highly variable. I also noticed hot-to-the-touch switch if I left the tranny in reverse. My switch must be acting like a thermal resistor! Yikes!

I'm going to replace the switch once again. I noticed that pelican offers 2 types - OEM and URO. Does anyone know if there is a difference? The OEM is 2x the price. I'm sure I didn't get OEM last time and maybe there is a quality difference. Ive had the car jacked up so many times, Ill probably break down and get OEM this time.

I'm also wondering if anyone measured the resistance or voltage drop across a perfectly working switch? Seems like you would only want 1-2 ohms max across that switch when in reverse. Any more and would would get heating with the amount of current in that circuit.

Its a real bummer not having backup lights. I cant tell you how many potentially bad collisions Ive had due to inattentive drivers in garages or lots. I avoid backing up out of spaces at all costs. A real hassle...

 

There shall be no resistance in the switch. This will cause heating and corrosion, causing more resistance.
Cheers,
Tore