: Stuck Top

Harry Yarnell
05-15-10, 07:25 PM
'05 XL
Top is down and secure, but it won't raise. The small panel that pops up first, does so, but that's it. Can hear subtle clicking (relays?) in the rear, but the trunk lid doesn't move. Any ideas where to start troubleshooting?
Is there a FAQ on this?

05-16-10, 02:51 AM

I feel your pain. I discovered my top wouldn't open two days after I bought my (out of warranty) vehicle.

Back on topic: The clicking sounds you're hearing are most likely the solenoids cycling on the Folding Top pump manifold, located in the left/rear trunk storage compartment. There are a number of things that can prevent the top from closing. Let's start with the easiest and work from there.

1) Is the engine running? Low battery power will cause all kinds of weird problems with this car. It's always a safe bet to raise and lower the Folding top with the ignition on and the engine purring away. Cycling the top two or three times in ACCY mode will drain the battery faster than say, Tiger Wood's harem. . . . On a slow night. . . When it's cold.

2) Since the Front Tonneau is operating (the three-piece panels behind the roll bars) you may have a bad Front Tonneau Position sensor if it isn't opening to its last open reference position.

--Each time the top is operated, the three position sensors (Front Tonneau, Rear Tonneau and Top Position) start from a known reference position that is updated and stored after each successful open/close cycle. As the mechanism moves, the sensor output changes voltage (read as counts on a dealer's Tech 2 scan tool) and is driven toward the reference position. When the mechanism stops movement, the actual position is compared to the stored reference position. If they don't compare (there's some tolerance built in to the software) the dreaded "Top Not Secure" message is displayed on the DIC and the next step in the cycle is aborted. The Rear Tonneau sensor is located on the front of the trunk behind the "curtain" that covers the linkages for the three sections. It's about 2" square with a small harness coming out of it with a connector; the unit is attached to a linkage. With the top stowed in the trunk, you probably won't be able to see it.

3) The next operation in the closure sequence is the Header Latch opening. (This could also be what you're hearing.) The header latch acts like a pair of "fingers" that closes around the windshield header and locks the top to the windshield frame after the two pins on either side of the roof engage. If the latch doesn't open after the Rear Tonneau raises, that will also stop the process. The header latch is operated hydraulically and has a switch to indicate if it is open or closed.

One of the worst case scenarios is a broken hydraulic line beneath the headliner. Since the lines curve to conform to the shape of the top and move with it, they can abrade and leak over time. The leak in the line not only keeps the header latch hydraulic cylinder from actuating, but the resulting leaking oil gets soaked up by the headiner and isn't always obvious until you've got a mini BP-sized oil slick under there. For piece of mind, inspect the top hydraulic oil reservoir level in the left/rear trunk storage compartment. The amber-colored oil level should be between the min/max lines. If it's low, DO NOT operate the hydraulic pump by pressing on the Top Control switch, as it will only make a bad problem worse.

4) At this point, with the hydraulic oil checked, it's probably best to raise the top manually and try to stow/raise it hydraulically again. If that doesn't work you can replace the Rear Tonneau Position Sensor (around $50 from gmpartsdirect.com) or have your local certified GM tech troubleshoot and repair it for you. If the Rear Tonneau is operating correctly, the sensor is likely good, so the header latch switch becomes the next likely suspect, --as long as the proper solenoid is operating to divert oil to the Header Latch hydraulic cylinder.

A good tech can plug a Tech 2 in and look at the sensor counts, solenoid activation, and switch positions to quickly determine where the problem lies. However you choose to troubleshoot this, please post what fixed it when you get this resolved. Every time someone reports a fix, we all learn from it and can better answer the next question.

If you have any more questions, don't hesitate to ask! Someone will know the answer!!


Harry Yarnell
05-16-10, 08:19 AM
Thanks CC, I'll do some sluthing. I've got the shop manual and they have a slew of DTC, but without the Tech tool they're useless. Does the XLR have onboard diagnostics like the Cadillacs of the '90's? Used to be able to press OFF and WARMER on the HVAC controls to pull up diagnostics, but didn't work on the XLR

05-16-10, 01:09 PM

The XLR only displays indications and status for various systems, but does not have built-in diagnostics. When connected, the Tech 2 runs a complete system diagnostic which displays DTCs for affected subsystems. The tool can then diagnose each subsystem in more thorough detail.

After buying and reading the shop manual, I realized how dependent the vehicle is on a Tech 2 to do any meaningful troubleshooting, so I finally broke down and bought one. It displays enough detail regarding the inner workings of the vehicle to make your brain hurt.

Understanding which step in the top movement cycle fails and what sensor is associated with the step is the key to diagnosing what might be wrong. The majority of the failures in the folding top appear to be sensors, which aren't horribly expensive, --just aggravating.

A bad sensor won't necessarily produce a DTC, and a Tech 2 isn't always needed to fix a top problem -but it sure helps! The sensors can be replaced without having to do a top re-learn, but a top re-learn must be performed after a mechanical repair. Hope this helps.


Harry Yarnell
05-16-10, 05:33 PM
In the 'old' days (80's-90's), you could press WARMER and OFF on the HVAC controls, and the DIC would display all stored trouble codes and whether they were current or history. When OB2 came in in '96, there was a multitude of codes for all the various systems. Great feature; no need for an external code reader. I wonder why they discontinued that.

05-16-10, 05:55 PM
When introduced, the XLR was the most complex car GM had ever mass-produced. Many of it's innovative features are still trickling into its line-up six years after their introduction. The current "it" car -the CTS-V, still doesn't have a HUD, which surprises me. What I initially thought was a gimmick, has proven to be one of it's best features.

XLR uses two data buses (a high and low speed) to communicate between its sub-systems, so an extra interface for the Tech 2 called a CANdi (Controller Area Network diagnostic interface) module is required. With all of this built-in complexity, it's little wonder that the majority of the owners are reliant on a dealership to diagnose and repair the vehicles being produced nowadays. Great for the dealers, not so good for the owners.

Harry Yarnell
05-20-10, 09:40 AM
Dealership called and said I had a code 1300; something about the two header switchs giving different signals (one closed and one open?). Hopefully to pick up later today and give a full report.

05-20-10, 10:59 PM
A double-header (switch) failure?!! Sweet. . .

DTC 1300 calls out the header latch switch circuit. There are actually two switches in the circuit that are checked by the Folding Top Control module, a latched and an unlatched switch. Your top should be ready in no time! Glad to hear it was an easy fix.

Harry Yarnell
05-21-10, 06:29 PM
Not sure what they did, but they corrected the two switch differences.
Checked yesterday to pickup, but the shop service writer said the tech went out on a 'test ride', over an hour ago, and hadn't returned..
Picked the car up today (with no obvious damage); $106.