Trunk Inoperative Using Trunk Button

[ECurtis]

Last Saturday was the first time in a long time that I was able to take the XLR on a long trip. Since I am in Davenport, Iowa now and have family in Chicago, Illinois I drove over to visit them and also avail myself of what the city had to offer. I stayed overnight and in the morning drove back. As I drove back in the morning I had the top down for part of the way. I needed to stop off for gas and I also decided to put the top up because it was getting too hot. I successfully put the top up, but then remembered that I wanted to get something from the trunk. I pressed the trunk button on the inside of the car and the trunk made an unlocking sound but did not move. I then tried to open it by depressing the trunk button on the back of the car and the same result. However, even though I could not open the trunk from the trunk buttons on the inside and outside of the car, I could raise and lower the top. Of course this meant that the trunk was operational, just not from the trunk buttons. This was very strange. The car had never done this before. I thought that there must be some fuse or something that was blown. I decided to address it when I got home. When I got home it did the same thing. However, I was able to open the trunk by pressing the button on the back of the car while simultaneously lifting the trunk. I had to depress the button about three times before it would release the trunk lid. Got the owners manual which said nothing about how to address this (of course). However, it did state that with the valet switch on the trunk could not open. I also got the impression that the top should not be able to go down or up. I thought that on the off chance maybe the valet switch was on (not likely, because I would have had to turn it on) but since the trunk should not open then it couldn't be the valet switch. Anyway, I opened the glove compartment (where the valet switch is located) and the valet switch was off. So it could not be the valet switch. However, just in case, I started the car and cycled the valet switch on and off twice. Lo and behold the trunk now opened when I depressed the trunk button on the inside or outside of the car.

So, if anyone else ever has this issue, where the top will deploy and stow but the trunk will not deploy using the trunk buttons on the inside or outside of the car, try turning off the car, then turning on the car and cycling the valet buttons on and off twice.

It worked for me.

I think that the car was just trying to give me a hard time. You know what, it worked!

 

[ccclarke]

------ I had the same symptoms you describe and it was caused by a faulty front tonneau sensor. If it comes back, start there.
CCC

 

[ECurtis]

------ I had the same symptoms you describe and it was caused by a faulty front tonneau sensor. If it comes back, start there.
CCC

Did you replace the sensor? If so, where is it and what was the cost of the sensor?

 

[SanDiegoXLR]

Wow- I've experienced your same problem a few times during my 4 years of ownership. Very frustrating! Thank goodness using the convertible raise/lower switch allows access to the trunk.

When having issues, I've tried the valet switch, but only one cycle....and not the 2 you described....so maybe that is the trick? Although, this might be a temporary fix?

Over the years, I've replaced 4 of the position sensors. Each was $54 from GMPartsDirect. GM PART # 19210515
Labor was around $110 each time.
First time they replaced 1 sensor.
2nd time they replaced 2 sensors.
3rd time they replaced the last 1 sensor.

Typically the repair would fix the symptoms for about 6-12 months, and then the glitches would appear again.
However, now that ALL 4 of the position switches/sensors have been replaced, I think it should be permanently fixed? (fingers crossed)
A bit of a pain, but WAY cheaper than the repairs Mercedes Benz SL500 owners face. Each module to repair on the SL500 is a minimum of $1500! And I think they have 6 modules for their top. OUCH!

So if you continue to have problems, you might want to just go ahead and replace all of the switches. Ends up being cheaper and less of a headache than bringing it in multiple times to the dealership.
Hope this helps,
-Mark

Did you replace the sensor? If so, where is it and what was the cost of the sensor?

 

[ccclarke]

The sensor in question is located between the seats at the front of the trunk area.

CCC

 

[ECurtis]

Mark,

Thank you! This was extremely helpful. The trunk did the same thing again last night. Only this time cycling the valet switch did not work.

Took it to the dealer today before I saw your response The dealer first said that the trunk struts were worn and needed to be replaced.

I questioned them about this for the obvious reason that if the struts were the problem why could the trunk open and close when the top is deployed?

They went back and investigated further. They said that for some reason the trunk sensor's lost their programing and that they were able to reprogram it.

Furthermore they said that they were working on it and it continues to work just fine. What? Was there some type of EMP (Electromagnetic Pulse) aimed at the trunk that de-programed the sensors? If so, why did the trunk still open

when the top was deployed? The service tech said that sometimes this happens to vehicles. He had not heard of it happening on the XLR, but they have only seen three in recent history, and mine is one of the three.

They still say that I need to replace the trunk struts. They say that one is not functioning properly and that the other one has to do all the work. Interesting, because when I watch the trunk deploy either up or down it does so

evenly. It does not seem as if one strut is malfunctioning. Even when I put the hood down manually, it seems to go down without smoothly and not at an angle.

Okay not to hijack my own thread, but has anyone else ever heard of their sensors losing programing and has anyone had to replace the hood struts?

 

[ECurtis]

The sensor in question is located between the seats at the front of the trunk area.

CCC

Thanks CCC

 

[hawkeye372]

I notice sometimes that mine gets caught on the right edges ( passenger side). when it's extremely hot out (over 90*f) then the trunk takes awhile to open. Usually after I've had it outside and heading home from a run. Also the edges where it's rubbing is turning white. But it's only noticeable when the trunk is open and you look over at the edge. But that's for letting us know of your problem and how to fix it. Ill keep an eye out and know what to ask for if this continues to bother me. So far I'm just blaming it on the heat wave we are having.

 

[ccclarke]

To answer your last two questions, the sensors don't lose their programming. The Folding Top Control module does. A couple of things can cause this, but generally, a sensor will wear out over time and give erroneous readings. The FTC module records these readings and matches them to a table of previously stored values. If they don't match within parameters, the module stops the movement operation to protect the hardware. If the sensors have been mechanically disturbed, that can change their reported values as well.

Once sensor (and switch) integrity is verified, the FTC is re-programmed with a new baseline value for the system sensors and switch positions. This is called a re-learn and is probably what your dealer performed. It takes just a few minutes using their TIS or Tech 2.

You asked about hood struts while commenting about the rear deck lid. Hood struts are easy to replace and aren't expensive. There was a thread here awhile back that pointed out a local source. I changed both of mine out in about five minutes.

--But back to what I think you were wanting info about: Rear deck lid struts aren't hard to replace, but can be a little messy. They can be found at any of the many online GM parts sources for a lot less than what a dealer would charge (about 40% off!) You should replace the hydraulic line O-rings if you do this yourself. There's an O-ring kit available too. I recommend investing in a set of shop manuals if you want to dig into your vehicle. They're well-written and eliminate any guesswork involved with doing the job right; especially where torque values for fasteners are concerned.

Hope this is of some use to you!

CC

 

[SanDiegoXLR]

Wow- sounds like your dealer is not very familiar with XLRs!
I cringe that as time goes on, finding experienced folks to work on our cars will be a challenge. Are you based in Victorville, CA? If so, it might be worth the 2 hour drive to San Diego to have Marvin K Brown work on your car....you could even ask for the same tech that worked on mine- my last name is Hendricks.

The service advisor at MKB is Kurt Stuessy- 619-291-2040.
The nice thing is there is a mall across the street with a large AMC movie theater and 2 story Target- so you could do that while they work on your car. To install the new switches only takes 1-2 hours, and they also wash your car for free with the service ;-)

I had the exact same problem as yours, and the issue was not the trunk struts.
Your logic is correct- why would the struts work fine with opening/lowering the top, but NOT work for opening the trunk?!

My struts have not been replaced. Only the position sensors (aka front tonneau position sensor) were replaced. And CC is correct- the trunk won't work consistently if the sensors aren't providing the correct response back to the Folding Top Control module
If you replaced all 4 sensors ($54 x 4 = $216) + $110 labor. So for about $316 you should have a permanent solution. I've been so happy that mine has not had a single glitch since the last sensor was replaced in March 2013. Prior to that, 60-70% of the time, the trunk release button on the fob did not work, and I'd have to start the ignition and use the convertible top button to have access.
-Mark

 

[mtrocket]

Each was $54 from GMPartsDirect. GM PART # 19210515
-Mark

So, all 4 sensors are the same part number???

 

[SanDiegoXLR]

I'm looking through all of my receipts, and it seems like the sensors are all the same part #.
I could have sworn I replaced 4, but maybe it was just 3 of them? Or perhaps the owner before me replaced 1 of them before I bought the car in 2009?

The technician could tell which ones had been previously soldered/replaced- apparently the repair is very obvious. And this time he said "Well, now they have ALL been replaced!" Hopefully the new factory parts will last.
-Mark

 

[SanDiegoXLR]

I just looked again on GMpartsDirect- apparently, in addition to the switch I posted about earlier (19210515), there are also:
Position sensor green for $46.84
Position sensor red for $47.36
I'm not sure how these are all different. For some reason I thought all the switches were the same, but just mounted in different places of the lid and top.

 

[ECurtis]

To answer your last two questions, the sensors don't lose their programming. The Folding Top Control module does. A couple of things can cause this, but generally, a sensor will wear out over time and give erroneous readings. The FTC module records these readings and matches them to a table of previously stored values. If they don't match within parameters, the module stops the movement operation to protect the hardware. If the sensors have been mechanically disturbed, that can change their reported values as well.

Once sensor (and switch) integrity is verified, the FTC is re-programmed with a new baseline value for the system sensors and switch positions. This is called a re-learn and is probably what your dealer performed. It takes just a few minutes using their TIS or Tech 2.

You asked about hood struts while commenting about the rear deck lid. Hood struts are easy to replace and aren't expensive. There was a thread here awhile back that pointed out a local source. I changed both of mine out in about five minutes.

--But back to what I think you were wanting info about: Rear deck lid struts aren't hard to replace, but can be a little messy. They can be found at any of the many online GM parts sources for a lot less than what a dealer would charge (about 40% off!) You should replace the hydraulic line O-rings if you do this yourself. There's an O-ring kit available too. I recommend investing in a set of shop manuals if you want to dig into your vehicle. They're well-written and eliminate any guesswork involved with doing the job right; especially where torque values for fasteners are concerned.

Hope this is of some use to you!

CC

This has been very, very helpful CC. Thank you. I will get a set of shop manuals. This sounds like a good project without too much difficulty. Also it did sound strange that the sensors would lose their programming. That is what the service rep said his techs told him. I am glad to get the straight story. Regarding the sensors failing, well I hope not, but if that is what is happening then okay. I did have to replace one or more a couple of years ago. Regarding something being mechanically disturbed. I don't know how that could have happened. I did not go near them. Anyway, as I said thank you. You have been extremely helpful!

 

[ECurtis]

Wow- sounds like your dealer is not very familiar with XLRs!
I cringe that as time goes on, finding experienced folks to work on our cars will be a challenge. Are you based in Victorville, CA? .......
-Mark

Mark, I cringe at the thought also. My biggest fear is that there is a lack of knowledge about the vehicle in general, especially in smaller markets. However, I am now in Iowa with the vehicle. I fly back and forth between locations and currently have the vehicle with me while I am here. I could possibly drive it to Chicago (3 hour drive), but would have to find a good shop to take care of it. However, that is somewhat impractical, especially if I have to leave the vehicle and then return to pick it up.

However, still something to consider.

 

[LVXLR8N]

Mark, I cringe at the thought also. My biggest fear is that there is a lack of knowledge about the vehicle in general, especially in smaller markets. However, I am now in Iowa with the vehicle. I fly back and forth between locations and currently have the vehicle with me while I am here. I could possibly drive it to Chicago (3 hour drive), but would have to find a good shop to take care of it. However, that is somewhat impractical, especially if I have to leave the vehicle and then return to pick it up.

However, still something to consider.[/QUOT
Question. Could a guy replace the sensors himself and then disconnect the battery and do the relearn thing with the windows and cycle the top?

 

[ccclarke]

Answer: No. Disconnecting the battery will force you to perform a window re-indexing. A re-learn of the Folding Top Control module (to ascertain the baseline sensor parameters) is a different thing altogether, and requires test equipment to write the values to the FTCs non-volatile memory. Disconnecting the battery will not alter the values stored there.

CC

 

[BusaMan]

Diagrams???

I'm evidently suffering from this "sensor amnesia" issue, as well. Can anyone post a diagram showing JUST where these little devils dwell? I've crawled all over the inside of my trunk (getting harder at my age...), and I haven't found anything except for some little devil on the driver's side trunk lifting mechanism, and it doesn't look much like a limit switch to me. It's about the size of a half dollar, and on the lifting arm for the trunk hood. Are these sensors potentiometers?

Tim

 

[ccclarke]

You are correct, the sensors are potentiometers. There are three. You've already found one on the driver's side scissor lift for the rear deck lid. That is the rear tonneau position sensor.

The front tonneau position sensor is visible from the rear of the car (with the rear deck lid raised) and is located on the forward wall of the trunk between the seats on the front tonneau mechanism. Earlier model XLRs have a fabric cover over the front wall which may obscure your view of this sensor.



The final sensor is located on the inside of the cabin on the left side of the roof adjacent to the speaker on the left side of the seat behind the roof's vinyl cover. This is the top position sensor.

The mechanism that locks the roof in place (it basically clamps the front of the roof to the windshield header) has an open and closed switch. You have to remove the headliner to view it. There's another switch on the passenger side of the windshield header that is activated when the top's locating pin goes into its receptacle.

The self-clinching latch on the rear of the trunk also reports its status to the folding top control module.

The switches are fairly reliable. The sensors are less reliable and account for the majority of the failures associated with the folding top. They either change tolerance over time, or become mechanically loose, (there's only one locating pin instead of a more reliable two) so the sensors are able to rotate around the single pin. After enough failures had been logged, a technical bulletin was issued to address this issue and position sensors were (supposd to be) epoxied in place during subsequent replacement. A more robust design would have used optical position sensors, but it is what it is.


Hope this helps a little.

CC

 

[BusaMan]

Huge help, "CC"; sure appreciate it. I'll check for any "loose" pot's. Which one "senses" the trunk hood being closed? The one on the scissor mechanism that I found?

Tim