Interior - Power Seats Intermittent Operation/Inop.
DTB
Date: September 26, 2008
Order No.: P-B-91.29/106a
Supersedes: P-B-91.29/106 dated April 3, 2006
Group: 91
SUBJECT: All Model 203, 209 and 211 Vehicles
Electrical Seat Position Adjustment (ESA) Not Working or Working Intermittently
If you receive customer reports in the above model vehicles that the electrical seat position adjustment (ESA) is not working or working intermittently, first follow normal diagnostic procedures to determine if it is a problem with the fuse, seat switch or ESA control unit. Before replacing the ESA control unit, follow the below diagnostic procedure as many ESA control units are unnecessarily replaced.
1. Check the part number of the ESA, the following only applies to part numbers A211 820 15 26, A211 820 16 26, A211 820 01 26, A211 820 02 26, A211 820 40 85 and A211 820 41 85.
2. Check that the fuse is okay. If not, replace fuse, verify seat functions normally and end test
3. Check with SDS that the seat is normalized in both directions,
i. Up to the middle of model year 2005, this can be checked with SDS by performing a quick test and then checking and clearing codes. Then with SDS, select the seat with the fault and with activations, move the seat through the full range of motion.
ii. As of the middle of model year 2005, perform a Quick Test. If the seat is not normalized, there will be a displayed after the line ESA driver - Electric seat adjustment driver (with memory) or ESA passenger - Electric seat adjustment front passenger (with memory). This is an indication that an event code has been stored. To view the event code, press F8 and then normalize using activations as described for vehicles up to the middle of model year 2005.
4. If a normalization error is stored without the corresponding Hall effect sensor error, the seat must be adjusted in both directions. This insures the Hall effect sensor error is reset. If there are no Hall effect sensor errors stored, it is sufficient to normalize the seat. Normalize seat with SDS by following the path: Control units -> Seats and doors -> ESA driver -> Electric seat adjustment driver (with memory) -> Control unit adaptations and then repeat if necessary for the passenger seat by selecting ESA passenger -> Electric seat adjustment front passenger (with memory) -> Control unit adaptations. If no Hall effect sensor error is stored, skip to step 9.
5. Using SDS, perform the following for each seat adjustment direction
i. Read status
ii. Delete error
iii. Activate motor in either direction for at least 2 seconds
iv. Read status
v. Activate motor in the opposite direction for at least 2 seconds
vi. Read status
6. If Hall effect sensor errors are still present, remove seat cushion according to WIS Document AR91.10- P-1070P (203/209) and for Model 211 refer to Group 91.10 for correct document based on Model Year and seat options of vehicle.
7. The electrical connectors for this function must be checked for loose contacts and the wires checked for short circuits. Disconnect the affected motor and Hall effect sensor. Check for the following:
i. a short circuit between the Hall effect sensor signal and ground wires
ii. a short circuit between the Hall effect sensor signal and motor line 1
iii. a short circuit between the Hall effect sensor signal and motor line 2
iv. a short circuit between the Hall effect sensor ground and motor line 1
v. a short circuit between the Hall effect sensor ground and motor line 2.
8. All resistance measurements must be greater than 1 Mohm
9. Check the rest current with a Digital Multimeter, this can be done at the fuse (use fuse adapter Special Tool W140 589 12 21 00). The following rest currents are measured with an electrical system voltage between 10 and 15 volts. With the CAN inactive, backrest locked and seat not moving <300 micro A, with the CAN inactive, door switches held closed, backrest folded and seat not moving <20 mA and with the CAN active and seat not moving <200 mA. If okay, go to step 12.
10. If the rest currents are greater than the above values, remove the following plugs one at a time to locate the cause of the high rest current.
i. Plug 11 - violet - Dynamic driving seat, if present
ii. Plug 8 - white - Head restraint and backrest switch, Coupes and Cabriolets only
iii. Plug 7 - pink - Backrest release switch, Coupes and Cabriolets only
iv. Plug 6 - orange - Backrest angle and head restrain height motors
v. Plug 5 - brown - Height adjustment motor at front of seat cushion
vi. Plug 4 - black - Fore/aft adjustment motor
vii. Plug 3 - green - Height adjustment motor at rear of seat cushion
viii. Plug 1 - black - CAN Bus and steering column adjustment motors
11. If the rest currents remain greater than the above values after all the above plugs have been removed, 2 the ESA control module must be replaced. Normalize seat, verify seat functions normally and end test. Please specify parts by VIN using EPCnet (Group 91/200).
12. The ESA control unit is good, continue to diagnose the system.
NOTE: The following allowable labor operations should be used when submitting a warranty claim for this repair. This information has been generated on September 26, 2008. Please refer to Netstar -> Star TekInfo -> Star Time for the most current labor time allowance.
In Case of Warranty
Operation: Short test, perform (54-1011)
Fuse - specify location, replace (54-1286)
Driver seat cushion, R&R (91-5008)
Front passenger seat cushion, R&R (91-5028)
Electric seat adjustment test, perform (91-0000)
Power seat memory control module - for driver seat, replace (after test) (91-6685)
Power seat memory control module - front pass. seat, replace (after test) (91-6690)
