Nightshift

XLR Retractable Roof Troubleshooting

6 posts in this topic

I've been having the odd problem with my roof lately. The dealer tells me I've got a couple bad switches that are intermittently acting up. The roof goes down ok, but sometimes will not go up. The trunk lid opens and the rear panel behind the seats flips up, but then it stalls and the hydraulics just bogs down.

I'd like to do my own troubleshooting but need a step-by-step guide so I can follow the order of things that have to happen in sequence. Does anyone have something like this? I'm sure that Cadillac dealers must have something to help their techs. I'm pretty sure all XLR owners would love to get their hands on something like this! Cheers, Bill

Share this post


Link to post
Share on other sites

I have been on this forum for a few years now and really don't see other xlr owners here. I would check out xlr-net ...on that site CC Clarke is very knowledgeable about the tops. I think you are going to need a tech2 in order to work on the top. Hate to send a guy to a different forum, but I peruse both daily.

Share this post


Link to post
Share on other sites

I have a 2006 FSM and looked at it. You need to get the OBD codes from a good code reader, or stop by an Autozone and get them to do a free OBD scan for you. There are scads of Bnnnn codes that will tell you what the problem is.

Here's one paragraph from the manual:

• Complete the check list, prior to performing the diagnosis:
- When the folding top control switch is pressed, check for driver information center (DIC) warning messages.
- Windows are normalized. Refer to Power Window Reinitialization.
- Luggage barrier is installed and secured, closing the luggage barrier switch.
- Vehicle is in PARK.
- Press the ignition to ACCY or RUN, with the engine OFF.
- Hydraulic fluid bypass valve in the operating position, turned clockwise, located above the pump motor.
- Operating temperature is normal.
• Whenever the open/close control switch is released or the top becomes inoperative in a suspended state, pressure will be maintained in the hydraulic system to avoid drifting and damage of components. After 4 minutes, the folding top module will gradually release the hydraulic pressure allowing the top to gradually settle to a resting position.
• When using the scan tool, the Rear Compartment Lid is referenced as the Deck Lid.
• If a repair is made to a signal circuit for a short to ground, test the component of that circuit for proper operation.
• Using the scan tool to access the History parameters for the folding top control (FTC) module, will display the last status of the items listed.

CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Share this post


Link to post
Share on other sites

Thanks guys. Appreciate the feedback. I'll check out XLR.net. Cheers, Bill

Share this post


Link to post
Share on other sites

This is definitely a job requiring a Tech 2 to diagnose and/or correct. Unfortunately, you need a certified XLR tech at a dealership to work on it unless you have your own Tech 2 and a set of Service manuals.

XLR Folding Top switches are fairly reliable, it's the potentiometers that determine moving component locations that aren't.

The pots-potentiometers for my fellow geeks, (or position sensors) are responsible for 90% of the problems associated with the Folding Top.

The position sensors (there are three) change their resistance when a component they're attached to moves. Each component has a retracted and extended position and corresponding resistance value (converted to counts by the Tech 2) depending on it's position. The Folding Top Control (FTC) module stores these values. Over time, it's very common for the values to drift as the sensors age, temperatures change, or they become loose -they're only held in place with one fastener. Once the expected (learned) sensor values don't match those stored in the FTC module, a Folding Top movement cycle (extend/retract) will stop. In many cases, when it stopped is an indicator of why it stopped.

The Folding Top follows a pre-programmed sequence. When retracting, first, the windows lower. If they aren't indexed, (so they know where their lowered position is, the top will not move.) Nada. Zip. Nothing.

If the windows are properly indexed, the front tonneau (three flaps behind the seats) raises, the rear deck lid raises, and the top retracts into the trunk. After that, the rear tonneau extends, and the rear deck lid lowers. To raise the roof, the opposite sequence occurs. Say for example, the folding top doesn't retract after the rear deck lid raises. (This assumes the hydraulic pump is good and the cantilever scissors mechanism that operates the rear deck lid is working properly too.) The front tonneau position sensor may be out of tolerance. Not enough to inhibit operation, but just enough to make the FTC module paranoid that it didn't raise, so it stops the cycle.

It takes more time to contort one's body to connect the Tech 2 than it does to run a full diagnostic on the XLR. One of the diagnostic subroutines deals specifically with the Folding Top. It displays the component values (counts) the FTC expects, and shows the actual counts it reads during a movement cycle. By recording the stored values, it's easy to determine which sensor is out of tolerance when it doesn't match up. If they don't match, a Relearn is performed. This procedure records the sensor position counts and over-writes the prior values. In many cases, a Relearn will fix a sensor problem. If the sensor is going (or is) bad, it's just a temporary fix, and the sensor will require replacement. Again, a Relearn is required.

This isn't meant to be a complete explanation of the Folding Top's operation, just a quick explanation of the most common problem most owners experience with it. 2004-2005 XLRs appear to be the most trouble-prone, and some changes (with retroactive mods) were made to the sensors in later years. But like anything else, as these vehicles age, they're going to need increasing amounts of TLC.

CC

Edited by CCClarke
Bruce Nunnally and Nightshift like this

Share this post


Link to post
Share on other sites

CC, thanks for this summary. Very helpful to understand and troubleshoot the roof down the road. Cheers, Bill

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.