Diagnostic Information for Power Folding Top - Stops Mid-Cycle, Deck Lid (Trunk) Inoperative, Intermittent Top Not Secure Message On DIC with No DTCs Set

This bulletin is being revised to add the 2007 model year and add some additional information. Please discard Corporate Bulletin Number 03-08-67-008A (Section 08 -- Body & Accessories).

This bulletin provides diagnostic information for a power folding top that exhibits the following conditions:

Technicians may find that no Diagnostic Trouble Codes (DTCs) have been set.

Intermittent concerns with top operation that do not set a DTC can possibly be related to top position sensors that read a position incorrectly. In such cases, the top will operate to a point and will not advance and complete the operation. In these cases, the pump will continue to run up to 15 seconds as long as the top control switch is depressed.

The top operates in a sequence of steps: the first step must be completed before the second step can start. The folding top control module reads the limit switches and position sensors (potentiometers) in order to determine if one step is complete and the next step can begin.

In order for a technician to diagnose a concern, it is important to assess and record the position of the top parameters where the roof stops (the location in the top operation sequence) and is unable to complete the cycle. It is also important to know the direction of operation, moving from top closed (coupe) to top open or moving from top open (convertible) to top closed.

Important: Performing a relearn procedure on the Folding Top Control (FTC) module will reset all of the reference parameters and the top will usually function again but the root cause of the concern will not have been corrected.

Before any movement of the folding top toward the open position is allowed, the following conditions must be met or top operation will be inhibited:

To cycle the top from the closed/coupe position to the open/convertible position, press the folding top control switch to the open direction and hold. The folding top status changes to Opening and the following steps will then take place:

1. The windows will express open (if closed).
2. The front tonneau (three piece closure behind the seats) opens. The header latch unlatches. This latch is located in the middle forward area of the roof panel. The deck lid/trunk lid opens.

Tip
If the top operation will not advance past Step 2, it is possible that:

•	The FTC module is not reading the Front Tonneau Position Sensor value at or above the Front Tonneau Open Reference Position Value.

•	The FTC module is not reading the Header Latch Limit Switches as Unlatched.

•	The FTC module is not reading the Deck Lid Ajar Status and Deck Lid Latch Switch as Deck Opened.

•	The FTC module is not reading the Deck Lid Extended as Active.

3. The top opens (roof retracts into the trunk).

Tip
If the top will not advance past Step 3, it is possible that the FTC module is not reading the Folding Top Position Sensor value at or below the Folding Top Open Reference Position value.

4. The rear tonneau (the retracted panel below the deck lid) extends.

Tip
If the top will not advance past Step 4, it is possible that the FTC module is not reading the Rear Tonneau Position Sensor value at or below the Rear Tonneau Closed Reference Position value.

5. The front tonneau closes. The header latch latches, securing the roof panel with the structure behind the seats.

Tip
If the top operation will not advance past Step 5, it is possible that:

•	The FTC module is not reading the Front Tonneau Position Sensor value at or below the Front Tonneau Closed Reference Position value.

•	The FTC module is not reading the Header Latch Limit Switches as Latched.

6. The trunk lid closes. Sequence complete.

Before any movement of the folding top toward the closed position is allowed, the following conditions must be met or top operation will be inhibited:

To cycle the top from the open position to the closed position, press the folding top control switch in the close direction and hold. The folding top status changes to Closing and the following steps will then take place:

1. The windows will express open (if closed).
2. The front tonneau (three piece closure behind the seats) opens. The header latch unlatches. This latch is located in the middle forward area of the roof panel and connects with the structure behind the seats. The trunk lid opens.

Tip
If the top will not advance past Step 2, it is possible that:

•	The FTC module is not reading the Front Tonneau Position Sensor at or above the Front Tonneau Open Reference Position value (counts).

•	The FTC module is not reading the Header Latch Limit Switches as Unlatched.

•	The FTC module is not reading the Deck Lid Ajar Status and Deck Lid Latch Switch as Deck Opened.

•	The FTC module is not reading the Deck Lid Extended as Active.

3. The rear tonneau (the extended panel forward of the deck lid) retracts under the deck lid.

Tip
If the top will not advance past Step 3, it is possible that the FTC module is not reading the Rear Tonneau Position Sensor at or above the Rear Tonneau Opened Reference Position value.

4. The top closes (roof extends to the windshield header).

Tip
If the top will not advance past Step 4, it is possible that the FTC module is not reading the Top Closed Limit Switch, inside the right hand guide pin receiver on the header, as Active/On.

5. The front tonneau closes. The header latch latches, securing the roof panel to the windshield header.

Tip
If the top operation will not advance past Step 5, it is possible that:

•	The FTC module is not reading the Front Tonneau Position Sensor at or below the Front Tonneau Closed Reference Position value.

•	The FTC module is not reading the Header Latches Limit Switches as Latched.

6. The trunk lid closes. Sequence complete.

The tables below show the change in sensor inputs to the FTC module as viewed on the Tech 2® as the roof progresses through the close and open sequence.

Important: Folding top operation that is free from intermittent failures to complete open or closing operations is dependent on consistent readings by the FTC module of the position sensors in the top assembly. A customer concern of incomplete top operations, when the pump continues to run with the control switch held down, may be due to inconsistent sensor readings. For example, during an open top operation, starting from the fully closed position, the front tonneau opens, the header latch unlatches, the trunk lid opens, the top retracts into the trunk and the rear tonneau extends. The next step of the sequence is the front tonneau closing and the header latch latching. If the front tonneau does not close and the pump continues to run with the control switch depressed in the open top direction, the system has failed to recognize the completion of the last step, which was the rear tonneau extending. If the rear tonneau has physically extended and the over-center links have locked in, then the probable cause of the failure is the rear tonneau position sensor reading incorrectly. In these cases DTCs are not set because the sensor is still reading inside a valid range. In this example the rear tonneau position sensor will be reporting MID to the Tech 2. If a customer concern is not repeatable by the technician then the following procedure can be used to diagnose a concern with the top position sensors.

Important: Performing a relearn procedure on the FTC module will reset all of the reference parameters and the top will usually function again but the root cause of the concern will not have been fixed.

Important: Cycling the top system repeatedly will cause the pump motor temperature to rise. If the pump gets too hot the system will suspend operation, send a "TOP MOTOR OVER TEMP" message to the DIC, and possibly set a DTC. The system can usually be cycled three complete opening and closings consecutively without overheating the pump motor. Allow at least 10 minutes after a "TOP MOTOR OVER TEMP" is observed before operating the top again.

The Tech 2 displays four parameters for each panel that uses a potentiometer to establish its position. Here is a definition of each:

Table 1 above shows the relationship of the position counts to the reference counts. As the rear tonneau is opening, the position counts are rising. As the rear tonneau is closing the position counts are lowering.

For the rear tonneau position to be considered open the position counts have to be equal to or higher than the open reference count. For the rear tonneau position to be considered closed the position counts have to be equal to or lower than the closed reference count. The front tonneau and top position sensor work the same way.

When the folding top position sensor is reading retracted it is at the low end of the scale and extended is the high end.

1. Check the system for DTCs. If any DTCs are stored, correct them first before performing the following procedure. Note that a B3670 (Top Motor Temp Circuit) can be set as a result of repeatedly cycling the top. If this code is stored, clear it and proceed.
2. If the top will not operate, check the DIC for messages while holding the top control switch down. The ignition must be in ACCESSORY or RUN, and power windows normalized.
3. Use the Tech 2 to view the FTC module inputs. Capture the following panel REFERENCE counts as indicated. The Tech 2 displays four parameters for each panel that uses a potentiometer to establish it's position. Refer to the definition list above for an explanation of these terms.

Use Table 3 below to capture the front tonneau, rear tonneau and folding top open and closed reference counts. The starting values can be captured before the roof is cycled. Cycle the roof either from the closed to open or open to closed position, stopping once the trunk lid has closed to capture the data. Start the engine before beginning to keep the system voltage stable.

Also observe the front tonneau, rear tonneau, and folding top position counts after each half cycle. If while the top is at rest, any of the position counts change by more than one count it is likely that a concern exists with the potentiometer installation. Readings that change more than one count at rest usually indicate excessive end load on the potentiometer shaft. Remove the potentiometer, and with a small sharp pick, attempt to clean out any foreign material or excess paint from the "D" shaped hole in the receiver and then reinstall it. The relearn procedure may be necessary if the top will not complete a cycle after the potentiometer is reinstalled. Remember to have the top in the fully open or fully closed position before running the relearn procedure. Rerun the reference count recording procedure as described above and once again observe the position counts while the top is at rest.

Important: If a panel will not reach a given state (stays in Mid) and the top stops moving, that panel's position sensor is likely at fault.

4. Review the REFERENCE counts you captured in table 3 below. Any position sensor that exhibits a variation of three reference counts or more from the start to the final cycle may require replacement. In the table 2 example the rear tonneau closed reference has a change of three counts from the second to third cycle. If the potentiometer readings indicate a variation of three or more reference counts then refer to the "Potentiometer Replace Note" below.
5. If a new potentiometer was installed then perform the top relearn procedure. After the system is relearned perform step 6. If no sensor was replaced continue to Step 6.
6. Update Procedure For ALL CARS Built Prior To April 2005 Vehicles built after April 2005 already have the updated FTC module software. The Tech 2 must have software version 25.009 or greater to perform this operation. Use the Tech 2 to recalibrate the FTC module. This procedure changes the open and closed reference calibration for the front and rear tonneau potentiometers on 2004 model year vehicles built prior to March 2004. The new calibration for vehicles built after this date will change the reference calibration for just the rear tonneau potentiometer. The path on the Tech 2 to the recalibration procedure is as follows: Build the Vehicle ⇒ Body and Accessories ⇒ Roof ⇒ Module Setup ⇒ Folding Top Module ⇒ Recalibration ⇒ Enter. The recalibration procedure can also be accessed through this path: Build the Vehicle ⇒ Computer and Integrating Systems ⇒ Module Setup ⇒ Folding Top Module ⇒ Recalibration ⇒ Enter. The Tech 2 will indicate when the operation is complete.

Important: Cycle the folding top system and verify normal operation.

7. If the folding top operates normally return the vehicle to the customer. If the folding top does not operate properly return to Step 1. The repeatability of the readings from the potentiometers should be examined very carefully.

Inspect the potentiometer attachment screw to be sure it is tight. A loose potentiometer will exhibit poor repeatability. Also inspect the involved linkage for binding or interference. The rear tonneau potentiometer's harness routing is critical. Refer to the graphics below for the correct routing. If an issue is identified within these areas, correct it first and then fill out Table 3 again to check the variation in the open and closed reference counts.

After the inspection above, the most common reason for a potentiometer to not have repeatable readings is poor fit (clearance) between the potentiometer's white D shaped shaft and the D shaped hole in the linkage it interfaces with. It is an interference fit by design so no play exists between the shaft and the linkage. For this reason it is important to be sure that the hole has no obstructions, such as residual epoxy from a previous repair. Carefully inspect the D hole to be sure the new potentiometer will completely engage the hole. If there is any epoxy present, pick it out with a thin sharp instrument, being careful not to enlarge the hole.

Important: Be sure to install the new potentiometer and wiring harness exactly as originally installed. Misrouting the wiring harness may lead to a wire pinch and/or possible linkage binding. Refer to the illustrations below for the correct wire harness routing. Repeat the folding top diagnostic test after all repairs are done to verify system integrity.

The illustration above shows the CORRECT routing of the rear tonneau position sensor located on the left hand trunk linkage. The protective sleeve (2) on the potentiometer wiring harness is routed underneath the wiring harness to the potentiometer connector. If the sensor currently on the vehicle is not installed exactly as shown in the illustration above, reinstall it as shown and described.

The illustration above shows an INCORRECT rear tonneau potentiometer wiring harness routing. The protective sleeve (1) is routed above the wiring harness to the potentiometer connector.

The illustration above shows a short loop of the vehicle's wiring harness to the potentiometer connector on the outboard side of the folding top linkage. This short exposed loop of harness is as designed and should not be tie strapped down or tucked into place.

For vehicles repaired under warranty, use: