A/T - Jerks When Stopping/DTC P1773/18181 Set
38 08 102010324/8
November 25, 2008.
Supersedes Technical Service Bulletin Group 37 number 08-01 dated January 4, 2008 for reasons listed below.
38 Vehicle shudders prior to stopping; possible MIL on (DTC P1773/18181 in TCM)
Condition
Vehicles with multitronic(R) gearboxes:
- Shortly before stopping, the vehicle jolts, and there may sometimes be difficulties when driving off again immediately afterwards. The complaint occurs only in D and S, and not in the tip gate.
- DTC P1773/18181 may be stored in the transmission fault memory.
- In many cases there is the additional complaint that when the gear lever is in D or R, the engine speed doesn't increase, the vehicle doesn't pull away, or the vehicle has no accelerator response. After an ON/OFF cycle, the vehicle accelerator response returns.
Technical Background
Because of dirt or a stiff valve, there is a hydraulic malfunction in the valve body. The cross flow at the valve presses the valve body piston into the created groove of the bore, and therefore it closes with jerks if the first gear is selected shortly before the vehicle stops. In individual cases, metal particles in the valve body may also lead to these problems. The juddering before stopping can mainly be observed below 12 mph in cold conditions. The complaint cannot occur in the tip gate, because in this mode the first gear is selected earlier.
Production Solution
Modified valve bodies:
- A4 (B6) from 8E-5A053574
- A6 (C5) from 4B-5N010000
- A6 (C6) from 4F-5N034000
Service
It is not necessary to receive an authorization number from the Technical Assistance Center for the repairs described in this bulletin.
Attach VAS scan tool printouts to repair order. Warranty request documents received without VAS scan tool printouts will be denied payment.
1. If DTC P1773/18181 is stored in the transmission fault memory, use Guided Fault Finding to locate the fault and make the necessary repair.
2. On vehicles from MY2003:
a. Read out value block 65 before the test drive. Note down the values.
b. Switch the ignition off and then on again.
c. Carry out a test drive with at least 20 stops to stationary (0 mph). Read out value block 65 again afterwards.
- If the value in MVB 65, position 2, is larger than the first time you read it out, then proceed according to the service solution below.
- If the value is smaller than at first or zero, then no repair to the valve body is necessary. See Additional Information.
Figure 1:
3. If the ATF is dirty, including rough metal particles larger than about 1 mm (Figure 1), replace the gearbox and the ATF pressure filter according to the repair manual.
Figure 2:
5. If no metal particles or only slightly shimmering ATF is found (illustration 2), change the valve body and ATF according to the workshop manual.
Attach all self-diagnosis protocols and measured value blocks to the valve body in the event of a warranty part request.
Use the following valve body:
- 01J 325 031 BC for vehicles without S program
- 01J 325 031 BP for vehicles with S program (e.g. from MY 04)
Warranty
When procedure applies to vehicles under warranty, use the following:
Additional Information
- MVB 65 counts the interventions of the safety valve (after recognized hydraulic malfunctions) to build the clutch pressure up - if required - in the shortest period of time. Because of that, on vehicles up to and including MY2002 without MVB 65, customers may report that the accelerator response is inoperative until the ignition has been cycled off and on. From MY2003 these safety valve interventions are counted in MVB 65. Additionally in MY2003, there is a flushing process that removes impurities from the valve body. A successful flush is recognizable by a decreasing value in MVB 65, 2nd position; the counter subtracts 1 from the stored value for every drive cycle (from ignition on to ignition off) without safety valve intervention.
- There is a delay in pulling away because after releasing the safety valve for the driving-off clutch, a new clutch program map must be programmed. This happens if the driver operates the brakes and the hydraulics generates a torque of 15 Nm on the clutch (this can be observed in MVB 10). If the driver releases the brakes during the programming process (max. 10 seconds), the clutch is kept open for safety reasons and the engine speed is prevented from rising. The programming process can be ended by switching the ignition off and on (resetting the control unit) and is then replaced by an adaptation during normal driving.
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service manuals for the latest information.