Body - Trunk Won't Open Fully/Opens Partially Closes
SI B51 07 05Body Equipment
February 2011
Technical Service
This Service Information bulletin supersedes SI B51 07 05 dated November 2005.
[NEW] designates changes to this revision
SUBJECT
Hydraulically Operated Trunk Lid (HKL) Troubleshooting Guide
MODEL
E65 and E66 (7 Series) equipped with HKL system (SA 316)
SITUATIONS
HKL system malfunctions can be difficult to diagnose. The following Troubleshooting Guide will aid in diagnosing HKL system malfunctions.
SITUATION A
The trunk lid will not open fully. The hydraulic pump makes a whining noise and the system is low on fluid.
SITUATION B
The trunk lid opens fully. It then drops slowly back to approximately half open.
Note:
This situation only affects vehicles produced before June 2003. For vehicles produced from March 2004, the trunk lid may drop slightly when it is opened for the first time after programming, resetting, replacement of the control module, etc. This is a normal situation. After this initial setting, the trunk lid will remain fully open.
SITUATION C
The trunk lid does not open or close fully. This situation may happen intermittently, depending on the outside temperature. Noises may also be heard from the hydraulic pump.
SITUATION D
The trunk lid only moves in one direction. When pressing the button to close the trunk lid, it tries to continue upwards after it has already been opened. In most cases, fault code OxA2B1 is stored in the HKL control module.
SITUATION E
The trunk lid does not stay open on a gradient of more than 10 degrees.
Note:
This situation only affects vehicles produced up to October 2004.
CAUSE A
The material used in the hydraulic lines allowed the hydraulic fluid to evaporate through the lines when the trunk area was heated to very high temperatures, such as when the vehicle was parked in the sun. The fluid loss caused by this heating is gradual, and the system continues to work properly until the fluid gets low enough that the pump runs out of fluid before the lid is fully open, or the fluid gets sufficiently aerated to cause the system to malfunction. Also, normal contraction of the hydraulic fluid due to low ambient temperatures could cause the system to malfunction in cooler weather, because the fluid level in the reservoir drops below the critical level.
CAUSE B
Weak trunk lid gas struts
CAUSE C
The connection between the hydraulic cylinder and the line is not tight.
Note:
For vehicles produced from March 2003 until December 2003, the trunk lid opening or closing forces may be too low, or the control module may have a coding error.
CAUSE D
The HKL control module is defective.
CAUSE E
The trunk lid gas struts are not designed for parking on extreme gradients.
CORRECTION A
Remove the right side trunk trim and check the fluid level in the HKL reservoir to determine whether it is low. The material used in the hydraulic lines was changed to prevent evaporation of fluid through the lines. The improved parts were introduced into production in March 2003.
CORRECTION B
Replace both trunk lid gas struts.
CORRECTION C
Check the hydraulic lines and the hydraulic fluid level. Also check the HKL control module coding index and replace or recode as necessary.
Note:
Do not replace the gas struts for this complaint.
CORRECTION D
Replace and recode the HKL control module.
CORRECTION E
Replace the right-hand side gas strut with an optimized part designed to withstand compression on extreme gradients.
PROCEDURE A
If the fluid level is low, remove the rear and left side trunk trim, and check the color of the print on the hydraulic lines. If the print is white, the hydraulic cylinder/lines assembly should be replaced with the improved parts as per Repair Instructions RA 51 24 151.
If the print is yellow, the improved parts have already been installed and the system should be checked for leaks or other problems.
The improved lines are available on hydraulic cylinder/line assembly part number 51 24 7 134 592. The lines may also be identified by the date code printed on the lines. Improved lines have date codes of 035/03 (day/year) and later.
Note:
The date code on the hydraulic cylinder is the week/year, and has no relation to the date on the lines.
PROCEDURE B
Follow Repair Instructions RA 51 24 300 to replace the trunk lid gas struts.
PROCEDURE C
1. Check to make sure that the connections between the hydraulic cylinder and the lines are tight.
2. Check the fluid level in the hydraulic unit reservoir by following Repair Instructions RA 51 24...
Note:
^ There are two different procedures to check the hydraulic fluid level. It is important to follow the correct procedure according to the production date of the vehicle.
^ If the fluid level is low and the vehicle was produced before March 2003, follow the procedure outlined in "Procedure A".
3. [NEW] Recode the HKL control module via CIP) 10.0 or higher by using ISTA/P.
[NEW] Note that ISTA/P will automatically reprogram and code all programmable control modules that do not have the latest software.
[NEW] For information on programming and coding with ISTA/P, refer to CenterNet / Aftersales Portal / Service / Workshop Technology / Vehicle Programming
Note:
Only a control module with a coding index of 03 can be coded. A control module with a coding index of 02 cannot be coded, and must be replaced.
[NEW] PROCEDURE D
Follow Repair Instructions RA 61 35 196 to replace the HKL control module. Recode the HKL control module via CIP 10.0 or higher by using ISTA/P.
Note that ISTA/P will automatically reprogram and code all programmable control modules that do not have the latest software.
For information on programming and coding with ISTA/P, refer to CenterNet / Aftersales Portal / Service / Workshop Technology / Vehicle Programming
PROCEDURE E
Follow Repair Instructions RA 51 24 300 to replace the right side of the trunk lid gas strut.
PARTS INFORMATION
[NEW] WARRANTY INFORMATION