VW Passat Transmission Range Switch Replacement

Just to keep things interesting, I got to help a friend out with their VW Passat that had a transmission issue.

This car has a bit of a back story. It belongs to Jim, who has done a couple of huge favours for us, including looking after Tess whilst we were homeless.

This Passat, a 2003 Passat V5 (B5.5 model), was Jim’s sons first car, and when his son upgraded to a later model VR6 Passat, it was up to Jim to sell this car on. He found a buyer, a family who wanted a cheap and tidy car to get around in.

Unfortunately, after a couple of days, the car developed a fault out of the blue, where it would go into limp mode when you selected reverse. Not ideal at all. Jim, being the good fellow he is bought the car back from the family and started to look into the issue.

The first issue he noticed was that the front carpets were soaked in inches of water. It appears the cowl drains are blocked and rainwater is flooding into the interior instead of draining away.

Jim dried all the moisture out and checked the transmission control unit, which for some stupid reason resides at the lowest point of the floor, in the driver’s footwell. The unit was dry, in a sealed box, but the issue remained.

Jim picked up an OBD2 scanner and came up with a 17090 code, indicating the Transmission Range Sensor was giving an incorrect reading.

A replacement switch was ordered, and that’s where I come into it.

After reading some sites, and watching some videos, I confirmed I had the tools and skills required to carry the job out, so I offered to help Jim out and replace the switch for him.

A very good video for this, which helped me a lot, is this one. It goes through all the steps needed to do the job, including a couple of extras if you have the heatshield and axle shield fitted (which this doesn’t).
https://youtu.be/tsgg8AyyTpE

I picked the car up last night, and confirmed the issue.

When you move the selector from P N or D, to Reverse, it would hesitate for a few seconds and then bang into reverse, and the selector indicator on the dash would light up solid red, indicating it was in limp mode. It also wouldn’t light up the 4 when selected.

In this mode, it shifts badly, and the only way to get it out of limp mode is to cycle the key off and on.

I scanned the car with both Jims, and my own scanner, and confirmed there was only the one code, 17090 or P0706. The OBD2 port is in the driver’s footwell, above the brake pedal.

The range switch lives on the side of the transmission, on the passengers side. It is hidden behind the transmission mount and bracket. With the car lifted, wheel off, you can see the mount and bracket.

Now, to replace the switch, that bracket needs to come off. As per usual, always disconnect the battery before working on anything electrical.

First, carefully support the transmission with a jack. I used a bottle jack, and a rubber block, lifting on the edge of the pan, where it is stronger. Only use enough force to support the trans, don’t try to lift it with the mount connected.

The large bolt from the mount to the bracket needs to be removed next. Its 16mm on the top of the bolt, and the nut on the underside is 15mm. I used a spanner on the top to stop the bolt spinning, and a rattle gun to remove the nut.

There are two bolts holding the mount on the underside and the big bracket is held on with three 8mm hex bolts. The one closest to the axle is longer than the other two.

To remove these I used a bunch of wobbly extensions. The two lower ones aren’t too hard to get to, but the top one is in line with the chassis rail and cannot be accessed without the wobbly flexibility.

They were all very tight, and even the rattle gun took some good ugga duggas to finally crack them.

This is the mount and bracket off the car

With that lot out of the way, the switch is now accessible

This is secured with two T27 Torx bolts, both of which double as mounts for brackets that secure the wiring

I also removed the bracket that secures the electrical connector. This is a 6mm hex. You can also slip the connector off this bracket instead of unbolting it, but if it’s been there a while it may be easier to remove the bracket on the bench instead of on the car. Having the wiring loose allows you then to disconnect the connector. These tabs are easy to break, so take care.

With that lot done, the whole switch just pulls free from the transmission and can be removed. Old with new

I moved over the two brackets

New switch fitted

It’s at this point that you should connect the new switch, make sure it’s firmly bolted in, reconnect the battery and turn the ignition to ON (but DO NOT START the car without the mount fitted) and move the shifter through its range and see if the issue is resolved. If it is, you should no longer see the red Limp Mode bar on the dash, and everything should light up correctly.

As you can see, this one was working perfectly now, selecting R and 4 with no issues. Now you can reinstall the mount and bracket and reassemble the car.

Unfortunately, I struck a small issue when reinstalling the mount, one of the bolts sheared off like it was made of butter.

Thankfully the mount is easy enough to remove, so with it on the bench I drilled into the broken bolt, and used a bolt extractor to remove it.

A new bolt and washer were sourced from my stash, and everything reassembled. Good save.

Before wrapping the job up, I wanted to have a check of the cowl drains and make sure they weren’t plugged, as this is the usual reason why the floors get soaked. That, and sunroof drains, but this car is a tin top.

The drains reside under this large panel at the back of the engine bay.

I don’t know if there are meant to be any clips holding it down, I suspect by the empty hole there should be one on the far LH side, but none were fitted here. Its a case of sliding the battery cover off (optional I guess), carefully pulling the rubber stripping off the front edge of the panel (this sandwiches the plastic panel to the metal panel under it, so remember that for reassembly) and then wiggling the panel out.

With the panel off, you have access to the battery, brake booster, and beneath them, the cowl drains. Pull the battery out (its not much fun to do) by removing the terminals and clamp, and then wiggling it up and out. I had to unclip the wiring harness that runs in front of the battery and move that aside, and then the battery came out in the space towards the cabin filter.

Under the battery is the battery tray (duh). Remove this by removing the three 13mm bolts/nuts, and it lifts out.

This gives access to the drains. The one under the battery is partly obscured by the AC pipes

The other, which I suspect you can access with the battery still in place, is under the brake booster. It’s hard to see, but you can feel it if you feel around in the area

The drain under the battery had some rubbish in it, but nothing major. It was a bit dirty, but nothing blocking it. The one under the booster, on the other hand, was completely plugged with leaves and other bits of foliage. It was also telling that there was water still sitting around the drain, despite the car having been in a garage drying out for a reasonable period of time.

I started clearing it by using my hand to pull out what I could, and stuck a finger into the drain and wiggled it around until it was clear. I then used some old fuel hose of the appropriate size, and gently pushed that down through both drains. I finished up by vacuuming around the area and sucking up what I could.

A quick squirt of water into the area showed that both drained freely, and water comes out from both sides under the car.

After reassembling the cowling, I fired the car up and confirmed that yes, it went into all gears, especially reverse, with no issues. No clunking, no lag, and no limp mode.

I plugged the scanner back in and cleared the codes. The code has not returned.

The car was returned to Jim this afternoon, who was happy to have it finally fixed, so now he can go back to selling it again. Typical that it ran with no issues for 4 years, and only faulted as soon as he sold it. Just VW life.

I’ll tell you what though, for a 220,000km early 00s VW, I was impressed by how nice it drove. Smooth, quiet and comfortable. Not quite exciting enough for me to own, but it will make someone happy for sure.