Troubleshooting Guidelines For the A5S 560Z

SUBJECT:
Troubleshooting Guidelines for the A5S 560Z

MODELS:
540iA, 740iA/iL

Situation:
To assist the technician in the diagnosis of complaints on this new transmission, we have developed the chart to share the collective experience up to this time.

Correction:
In addition to reviewing the chart, the following hints will assist the technician in performing a systematic diagnosis. In many instances involving shift complaints and/or speed sensor faults with no apparent defect, it is recommended to verify the current transmission control module software version and update the transmission control module EPROM if it is not the latest version, C2729X. The software version will be shown on the transmission control module identification page under "Serial No." using either the Service Tester or MoDiC.

NOTE:

Please reference S.I. 24 01 93 (3748) in regards to the necessity of obtaining a hotline contact number prior to replacing an A5S 560Z transmission

I. Basic Troubleshooting

Many complaints regarding transmissions are attributable to conditions seemingly unrelated to proper transmission operation. Therefore, diagnosis should begin with the following basic checks:

- Read out the transmission and engine control module diagnostic trouble code memories with the explanation of any trouble codes stored. Always work on eliminating faults stored in the engine control module first, since those stored in the transmission control module may only be a consequence of the engine control module fault.

- Leaks (an obvious sign indicating the need to check fluid level before proceeding.)

Ensure that battery voltage is greater than 12.5 V with the ignition switched off and that it does not drop below 9.4 V under any electrical load, in particular during cranking. A voltage below 9.4 V will cause the Failsafe program to be activated.

Battery connections:
Check tightness of positive/negative leads and ground strap.

Visual check of electrical connections/cables, particularly the connector at the transmission.

II. Road Testing

Many automatic transmission complaints refer to specific shift actions. To ensure an accurate diagnosis and repair, the shifts which are the subject of the complaint must be evaluated on the road. In many cases, if the complaint is clearly defined an equally specific solution can be found.

If traffic is heavy, you may not always be able to obtain the desired transmission shifts or you may not be sure what gear the transmission is in at the given time. Move the selector lever carefully and note the reaction if you are not sure in which gear the transmission is actually operating at the given time.

Example 1: You are driving in selector lever position D and in the E program at 35 mph and constant load. Theoretically, the transmission could be in either 3rd or 4th gear. Move the selector lever from D to 3. If the engine speed increases, 4th gear was in use. If the engine speed does not change, 3rd gear is in use.

Example 2: You suspect that the 3-2 shift is poor when the accelerator pedal is depressed after a period of coasting. Select position 3 so that the transmission cannot upshift beyond 3rd gear. This will prevent 4th gear from being engaged when the car is coasting.

III. Note on electric power supply

If the voltage of the power supply is too low, the Failsafe program may be activated and non-plausible diagnostic trouble codes may be indicated. Note that the voltage in the vehicle's electrical system must not fall below 9.4 V under any electrical load, in particular during cranking.

IV. Checking ground connection

Loose connections or open ground wires can initiate the Failsafe program or set non-plausible diagnostic trouble codes. A check of the following ground points is recommended (are they painted over, loose, improperly crimped, etc.?).

- Ground connection point on outer right rear seat base, X497 (under a plastic cover).

- Ground points on right hand rear of firewall next to electrical component box (E-box), X6452 and X6453.

The ground wiring stated above is shown in the 1993 BMW 740i/750iL (E32) Electrical Troubleshooting Manual under Groups 0670, 7000 and 7100.

V. Fluid level checking procedure

The oil level in replacement transmissions is correct and need not be checked, nor is it necessary to check the oil level during the Quality Certification I (QC I) or Quality Certification II (QC II).

In the event of a complaint, checking the oil level may be useful if there is evidence of leakage or if it is suspected that work has already been undertaken on the transmission.

The following procedure supersedes any previously published procedure on oil level checking for the A5S 560Z and must be followed carefully to ensure a proper oil level.

1. The vehicle must be without load and standing on a flat, level surface. With the engine running switch on the low-beam headlights or the air conditioning. This will increase the idling speed and ensure that the transmission's oil pump supplies a sufficient volume of oil to reliably maintain all oil passages filled with oil.

2. The transmission temperature must be between 20~C and 30~C before beginning the checking procedure. Use the Service Tester or MoDiC to determine the transmission oil temperature.

3. Step on brake firmly, apply parking brake fully and move the gear selector lever several times in succession through each gear position, pausing briefly in each gear.

4. With the engine running and the selector lever in PARK or NEUTRAL position, remove the filler plug located in the bottom of the oil sump.

Note that some oil will always be trapped above the plug and run out when the plug is removed: this is not an indication of proper filling or overfilling.

5. Add the specified oil until it starts to overflow.

6. With the engine running, reinstall oil filler plug (tightening torque 100 N-m).

SPECIAL NOTES ON OIL LEVEL CHECKING

It is preferred to begin checking with an oil temperature of 20~C and be prepared to reinstall the oil filler plug at 30~C. The transmission will hold an extra 0.6 liter of oil this way versus topping up at 50~C.

If the oil temperature rises above 50~C during the checking procedure, the resulting oil level will be too low.

If there is a suction sound during the fill-up procedure air is being sucked in at the oil pick-up. This must be avoided as it will cause oil foaming resulting in a reduced oil level. If oil foaming is suspected, shut-off the vehicle and repeat the fill-up procedure after waiting a few hours for the oil to settle down.

VI. Adding oil (ATF) after repairs

1. With the engine stopped, add oil to the transmission until it overflows.

2. Insert and tighten the filler screw, select PARK position and start the engine.

3. Remove oil filler plug and add oil until it overflows.

4. Check the oil level as detailed in item V.

VII. Notes on fitting an exchange transmission or a Service EPROM

When replacing a transmission or a transmission control module EPROM because of a shift complaint, the previously stored adaptation values must be cleared. This is most easily accomplished using the Service Tester or MoDiC and Selecting "Special Functions" to clear the adaptation values.

Alternatively, the adaptation values may be cleared by leaving the transmission control module disconnected from the harness for a period of 1 hour.

After clearing the previously stored adaptation values carry out the adapting procedure as detailed in item VIII.

VIII. Adapting procedure after transmission exchange or software update.

The transmission control module is capable of adapting clutch apply pressure, within narrow limits, so that optimum shift refinement is achieved. After a transmission has been exchanged or the control module replaced/updated, all upshifts must be carried out several times in the E program and selector lever position D at various constant accelerator pedal settings.

Always check shifts several times if they were the subject of the customer complaint. It is important to maintain a constant throttle during the adaptation process as no adaptation will take place if the throttle position is not held constant during the shift.

Note:
If the transmission control module is disconnected from the electric power supply for more than 30 minutes, the adaptation values in memory may be lost and the adapting procedure must then be repeated.

IX. Note on checking the torque converter stall speed

In some cases, the diagnostic procedure may call for the stall speed to be checked. When checking stall speed, observe the following points:

- No personnel may be in front of the vehicle while testing.

- Service brake and parking brake to be fully applied.

- Select gear position 2.

- Depress the accelerator pedal fully to the kickdown position (for a maximum of 5 seconds) and observe maximum RPM obtained on tachometer.

WARNING:
To avoid the risk of overheating, do not check the stall speed for more than 10 seconds and allow to cool down for 15 minutes before repeating the test.

X. Additional Technical Assistance

In cases where the above hints and the chart do not help in locating the fault in a timely manner, please contact the Technical Liaison for ZF

Products through the BMW Technical Hotline.