Test Procedure
Measuring Battery Voltage Using the Midtronics MCR 717Follow the steps below to measure the battery charge level. Refer to WIS document AR54.10-P-1129-01A, and STAR Bulletin S-B-58.00/124A.
1. Make sure the vehicle is not running.
2. Turn off all electric consumers (i.e. radio, ignition, headlamps, etc.).
3. Make sure the SmartKey is not in the electronic ignition switch (EIS).
4. Connect the Midtronics MCR 717 tester to the battery.
5. Follow the Midtronics MCR 717 menu selections.
6. Perform a battery-conditioning test.
7. Review the test results.
Measuring Battery Voltage Using a Digital Multimeter
Follow the steps below to measure the battery charge level.
1. Make sure the vehicle is not running.
2. Turn off all electric consumers (i.e. radio, ignition, headlamps, etc.).
3. Connect the digital multimeter (DMM) to the battery.
4. Switch the SmartKey to "position 1."
5. Turn on the low-beam headlamps.
6. Wait 10 seconds.
7. Measure the battery charge level with the digital multimeter.
8. Turn off the headlamps and ignition.
Note:
To be accepted, warranty claims for batteries must have:
Midtronics MCR 717 test code on the repair order
Midtronics MCR 717 test code entered in the message field on the warranty claim
Accurate diagnosis of failed batteries with battery voltages less than or equal to 10.2 V is not possible. Recharge the battery in such a case. If the battery voltage falls between 10.3 V and 11.9 V, recharge the battery in accordance with WIS document AR54.10-P-1130T. Measure the battery voltage again after installation of the new battery or after a jump-start. Return the vehicle to the customer if the battery voltage is greater than or equal to 12 V but first perform thorough diagnostic tests (e.g. "Control Module Isolation for Rest Current Measurements Procedure") at the workshop to be sure the condition is not intermittent.
Measuring Rest Current
Measure the rest current according with the following procedure if the battery voltage is greater than 10.2 V. Meet the following conditions before measuring the rest current.
1. In the event of a newly replaced battery, cycle the ignition key ON and then OFF to reset the control modules.
2. Turn off the ignition and remove the key.
3. Close the hood, doors, and glove box.
4. If KEYLESS-GO equipped, make sure the KEYLESS-GO key is not within antenna range while measuring the rest current.
5. Inspect the COMAND system for a navigation or music CD. Remove any CDs from the system, as this will affect the rest current.
6. Remove the cellular telephone, if so equipped.
Note:
Connect the digital multimeter to the battery before disconnecting the negative battery terminal to avoid disrupting the electrical system and to ensure the control units will not require normalization.
Measure the rest current by connecting the digital multimeter to the battery in the following manner:
1. Connect the multimeter positive terminal (red) to the negative battery cable ground at the body attachment point.
2. Loosen, but do not remove, the negative battery cable terminal.
3. Connect the multimeter negative terminal (black) to the negative battery post, underneath the battery cable terminal.
4. After the multimeter is connected, remove the negative cable at the battery post.
5. Manually latch the trunk lid.
6. Globally lock the vehicle.
7. Wait approximately 10 minutes after locking the vehicle.
8. Once the CAN bus enters "rest state," do not disturb the vehicle (i.e. do not unlock the vehicle; do not disturb the door handles; etc.).
> Repeat the rest current measuring procedure if the rest current is > than 60 mA.
> Perform further diagnostics, including the procedure outlined in diagnostic flow chart # 4, "Control Module Isolation for Rest Current Measurements Procedure."
> Return the vehicle to the customer if the rest current is less than or equal to 60 mA but perform thorough diagnostic tests to make sure the condition is not intermittent. Refer to WIS document AR54.10-P-1030T.
Battery Cable Connection Check
Poor battery contacts can result in battery/starting problems. Therefore, check the following cable connections for proper contact:
Both battery posts
G1 positive circuit at pre-fuse box (F33)
F78; F79; F80; F81 power supply circuits at pre-fuse box (F33)
Inspect the bolted connections at the battery control module for proper torque. Check the connection to the body-connections should be clean and free of corrosion.
Battery Charging
If the battery requires charging during troubleshooting procedure, refer to WIS documents AR54.10-P-1130T AS54.10-Z-0001-01A, 0S54.10-P-0001-01Z, AH54.10-P-0001-01A, and AH54.10-P-0002-01A for instructions.
Normalizations
Normalize all affected control units if, during the troubleshooting procedure, the battery was disconnected.
Refer to WIS document AR00.19-P-0200T.
Advanced Diagnostics
Have the vehicle transported to a local authorized Mercedes-Benz dealership workshop for further diagnostics if remote repair is not possible. The workshop technician should begin troubleshooting using diagnostic flow chart # 2 Central Locking System Test" The technician should also perform the procedure outlined in diagnostic flow chart # 4 "Control Module Isolation For Rest Current Measurements Procedure."
Control Module Isolation for Rest Current Measurements Procedure:
Multiple digital multimeters are necessary to isolate the vehicle electrical system. This procedure requires six digital multimeters and one Star Diagnosis Hermann HMS 990 or equivalent oscilloscope/multimeter be used. The six multimeters monitor each isolated circuit (Figure 1) for rest current, while the SDS Hermann HMS 990 meter or oscilloscope/multimeter monitors the CAN-B bus for activity. Fewer than six digital multimeters can be used for this procedure, but the Control Module Isolation for Rest Current Measurements Procedure" would otherwise need to be performed multiple times to obtain the current draw for the six electrical branches.
The entire vehicle rest current is summed up as follows:
^ DMM6 = Total Rest Current (approximate value = 20-60 mA)
^ DMM5* = F33 (Rear Pre-Fuse Box) Rest Current (approximate value = 20-36 mA)
*DMM5 = (DMM4+DMM3+DMM2+DMM1+F33 Remaining Amperage)
^ DMM4 = F34 (Interior Fuse Box) Rest Current (approximate value = 10-25 mA)
^ DMM3 = N10/1 (Driver SAM Circuit 15) Rest Current (approximate value = 0 mA)
^ DMM2 = N10/2 (Rear SAM) Rest Current (approximate value = 6-35 mA)
^ DMM1 = N10/1 (Driver SAM) Rest Current (approximate value = 1-3 mA)
^ Remaining Amperage = Sum of F33 lower electrical branch (N82, A34/4, A35/11, X58/1, and M40/1)
^ DMM6 - DMM5 = F32 (Front Pre-Fuse Box).
1. Access the rear pre-fuse box to connect the multimeters (Figure 2). Refer to WIS document AR54.15-P-1340TA.
Note:
DO NOT remove the rear pre-fuse box. Note the original location of the supply-line circuits before removing them-reinstall supply-line circuits in their original location.
2. Connect DMM6 to the main battery G1, as described in Measuring Rest Current".
3. Disconnect the G1 positive circuit from control module F33. Connect DMM5 between F33 and the G1 positive circuit.
4. Disconnect the f81 supply-line circuit from control module F33. Connect DMM4 between F33 and the f81 circuit.
5. Disconnect the f80 supply-line circuit from control module F33. Connect DMM3 between F33 and the f80 circuit.
6. Disconnect the f79 supply-line circuit from control module F33. Connect DMM2 between F33 and the f79 circuit.
7. Disconnect the f78 supply-line circuit from control module F33. Connect DMM1 between F33 and the f78 circuit.
8. Access the X30/4 CAN-B bus connector to connect the Hermann HMS 990 or oscilloscope/multimeter.
Refer to WIS document GF00.19-P-1000-05DA.
9. Separate the X30/4 connector. Refer to WIS document S154.18-P-0004A.
10. Plug the CAN-B bus banana plug harness (P/N 220 589 00 99 30) into the X30/4 connector.
11. Connect the Hermann HMS 990 or oscilloscope/multimeter to the banana plugs. Refer to Hermann HMS 990 Connection & Installation".
12. Make sure the hood and all doors are completely closed. Manually latch the trunk, and globally lock the vehicle with the SmartKey.
13. Leave the vehicle undisturbed for at least 1% hours so all control module rest currents can stabilize.
14. Verify the CAN-B bus is not active by monitoring the Hermann HMS 990 or oscilloscope/multimeter.
The CAN-B bus is comprised of a two-wire circuit-CAN-High and CAN-Low.
When measuring CAN-B bus activity using the Hermann HMS 990 oscilloscope, the CAN-High has an approximate voltage of 0.5 volts at rest and 4.5 volts when communicating. CAN-Low has an approximate voltage of 12.5 volts at rest and 0.2 volts when communicating.
Voltage readings differ when measuring CAN-B bus activity with a multimeter or a conventional oscilloscope. CAN-High has an approximate voltage of 0.025 volts at rest and 0.65 volts when communicating. CAN-Low has an approximate voltage of 11 volts at rest and 4.65 volts when communicating.
15. Monitor each digital multi meter for excessive rest current. If a multimeter indicates abnormal current draw, further diagnostics are necessary within the affected circuit. Determine which control modules are contained within the circuit to further isolate the circuit. Identify the suspect control module and then either disconnect the individual control module, or remove individual fuses and relays from the corresponding SAM or fuse box. Monitor the digital multimeter for sudden rest current reduction. Control modules, fuses and relays that cause sudden, drastic current reduction will likely be the corresponding circuit causing the abnormal current draw. Additionally, inspect the wire harness and connector terminal pins for abnormal current draw.
Hermann HMS 990 Connection and Installation
1. Connect the interface cable between the Hermann HMS 990 and Star Diagnosis.
2. Connect the power cord to the Hermann HMS 990.
3. Connect the 7-pin cable to "scope A" of the Hermann HMS 990.
4. Connect pin A4 to the black banana plug [CAN-B bus banana plug harness (P/N 220 589 00 99 30)].
5. Connect pin A1 to the red banana plug [CAN-B bus banana plug harness (P/N 220 589 00 99 30)].
6. Connect the black pin to a suitable vehicle ground.
7. Restart Star Diagnosis.
DO NOT connect the Star Diagnosis OBD II cable to the vehicle diagnostic connector.
8. Launch the Hermann HMS 990 by double-clicking on the HM5990 icon in Star Diagnosis.
9. Select Oscilloscope."
10. Select Universal Scope."
11. Select Electronic Systems" from the pre-settings tabs.
12. Select "Channel A" from the lower tool bar.
13. Select "Interior Compartment CAN-HI (as of VV220)" from the "Electronic Systems" list.
14. Select "Channel B" from the lower tool bar.
15. Select "Interior Compartment CAN-LO (as of W220)" from the "Electronic Systems" list.
16. Double-click on "Interior Compartment CAN-LO (as of VV220)" to view the waveform.
Use the following parameters to view the CAN waveforms.
Roadside Assistance Flow Chart
Central Locking System Test
Battery Voltage Condition Test
Rear SAM Bit-Flipper Checking Procedure