Mercedes-Benz Sprinter / Dodge Sprinter. Manual - part 542

TEST

ACTION

APPLICABILITY

Turn the ignition on.
While back probing any module harness connector that uses the CAN Bus, measure
the voltage between the CAN C Bus (+) circuit and ground.
While back probing any module harness connector that uses the CAN Bus, measure
the voltage between the CAN C Bus (-) circuit and ground.
Is the voltage above 3.0 volts for either circuit?

All

Yes

→ Go To 5

→ Go To 6

Turn the ignition off.
Using a voltmeter, connect one end to the CAN circuit that previously measured
above 3.0 volts, and the other end to ground.
NOTE: When performing the following steps, turn the ignition off and WAIT
ONE MINUTE, before disconnecting any module. Repeat this for all mod-
ules, failure to turn off ignition may result in damaging the disconnected
module.
Turn the ignition on.
Disconnect a CAN Bus module the vehicle is equipped with. Monitor and note the
voltmeter reading.
NOTE: Repeat the above step for each CAN Bus module until all the modules
have been disconnected.
NOTE: Refer to the wiring diagrams in the service information to help
determine which modules are on the CAN Bus.
Is the voltage steadily above 3.0 volts with all the modules disconnected?

All

Yes

→ Repair the CAN C Bus (+) circuit and/or the CAN C Bus (-) circuit

for a short to voltage.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

→ Replace the module that when disconnected, the short to voltage

was eliminated.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

Turn the ignition off.
Disconnect the negative battery cable.
While back probing, measure the resistance between ground and the CAN C Bus (+)
circuit.
While back probing, measure the resistance between ground and the CAN C Bus (-)
circuit.
Is the resistance below 50.0 ohms for either measurement?

All

Yes

→ Go To 7

→ Go To 8

TRANSMISSION - NAG1

CAN BUS CIRCUIT —

Continued

TEST

ACTION

APPLICABILITY

Turn the ignition off.
Disconnect the negative battery cable.
Using an ohmmeter, connect one end to the CAN Bus circuit that previously
measured below 50.0 ohms and the other end to ground.
While monitoring the ohmmeter, disconnect a CAN Bus module and record the
reading.
NOTE: Repeat the above step for each CAN Bus module until all the modules
have been disconnected.
NOTE: Refer to the wiring diagrams in the service information to help
determine which modules are on the CAN Bus.
Is the resistance below 50.0 ohms with all the modules disconnected?

All

Yes

→ Repair the CAN C Bus (+) circuit or the CAN C Bus (-) circuit for

a short to ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

→ Replace the module that when disconnected, the short to ground

was eliminated.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

All

Yes

→ Go To 9

→ Go To 10

Turn the ignition off.
Disconnect the negative battery cable.
Disconnect the SKREEM harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between the CAN C Bus (+) circuit and the CAN C Bus (-)
circuit at any CAN Bus module harness connector.
Disconnect each CAN Bus module harness connector the vehicle is equipped with,
one at a time, while monitoring the resistance.
NOTE: Refer to the wiring diagrams in the service information to help
determine which modules are on the CAN Bus.
Is the resistance below 50.0 ohms after disconnecting all the modules?

All

Yes

→ Repair the CAN C Bus (+) circuit for a short to the CAN C Bus (-)

circuit.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

→ Replace the module that when disconnected, the short was

eliminated.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

TRANSMISSION - NAG1

CAN BUS CIRCUIT —

Continued

TEST

ACTION

APPLICABILITY

Turn the ignition off to the lock position.
Disconnect the ECM harness connector.
Measure the resistance between the CAN C Bus (+) and CAN C Bus (-) circuits in the
ECM harness connector.
Is the resistance 120.0 ohms ± 5.0 ohms?

All

Yes

→ Replace the ECM per the Service Information.

Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

→ Go To 11

Turn the ignition off to the lock position.
Reconnect the ECM harness connectors.
Disconnect the SKREEM harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the CAN C Bus (+) circuit and the CAN C Bus (-)
circuit in the SKREEM harness connector.
Is the resistance 120.0 ohms ± 5.0 ohms?

All

Yes

→ Replace the Sentry Key Remote Entry Module per the Service

Information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

→ Repair the CAN C Bus (+) and/or CAN C Bus (-) circuit for an

open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

Turn the ignition off to the lock position.
Disconnect the negative battery cable.
Disconnect the TCM harness connectors.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the CAN C Bus (+) circuit and the CAN C Bus (-)
circuit at the TCM harness connector.
Is the resistance 60.0 ohms ± 5.0 ohms?

All

Yes

→ Replace the Transmission Control Module per the Service Infor-

mation.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

→ Repair the CAN C Bus (+) and/or CAN C Bus (-) circuit for an

open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

TRANSMISSION - NAG1

CAN BUS CIRCUIT —

Continued

Symptom:

CAN MESSAGE FROM ECM FROM SLA

When Monitored and Set Condition:

CAN MESSAGE FROM ECM FROM SLA

When Monitored:

Set Condition:

CAN Bus message received from the Shift Lever Assembly are incorrect.

POSSIBLE CAUSES

CAN BUS CIRCUIT DTC PRESENT

SHIFT LEVER DTCS PRESENT

OPEN CAN BUS CIRCUITS AT SHIFT LEVER

SHIFT LEVER ASSEMBLY

TEST

ACTION

APPLICABILITY

NOTE: Low fluid level can be the cause of many transmission problems. If
the fluid level is low locate and repair the leak then check and adjust the
fluid level per the service information.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIII

t, read the engine DTCs. Check and repair all engine DTCs prior to

performing transmission symptom diagnostics.
With the DRBIII

t, read and record all Transmission DTCs.

NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal
connections can set DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Most DTCs set on start up but some must be set by driving the vehicle such that all
diagnostic monitors have run.
Note: Verify flash level of transmission controller. Some problems are
corrected by software upgrades to the transmission controller.
NOTE: Check for any Technical Service Bulletins that may apply.
Perform this procedure prior to Symptom diagnosis.

All

Continue

Go To

Ignition on, engine not running.
With the DRBIII

t, read Transmission DTCs.

NOTE: If the DTC, CAN BUS CIRCUIT, is present, perform diagnostics on
that symptom first.
Is the DTC, CAN BUS CIRCUIT, present?

All

Yes

→ Refer to the Transmission category and perform the appropriate

symptom.

→ Go To 3

TRANSMISSION - NAG1

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