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SUBJECT

DATE

SPN 168 (ACM) (GHG17)

May 2016

Additions, Revisions, or Updates
Publication Number / Title
DDC-SVC-MAN-0191

Platform

Section Title

DD Platform SPN 168/FMI 1 - GHG17

Change
Changed graphic and added pin out locations

DiagnosticLink users: Please update the troubleshooting guides in DiagnosticLink with this newest version. To update the
tool troubleshooting guide, open DiagnosticLink and from the Help – Troubleshooting Guides menu, select the appropriate
troubleshooting manual, then click Update.

All information subject to change without notice.

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Copyright © 2016 DETROIT DIESEL CORPORATION

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2 SPN 168/FMI 1 - GHG17

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SPN 168/FMI 1 - GHG17

Battery Voltage Low
Table 1.
SPN 168/FMI 1
Description

Battery Voltage Below 10.5 Volts

Monitored Parameter

ACM Battery Voltage

Typical Enabling Conditions

Key ON Engine OFF

Monitor Sequence

None

Execution Frequency

Always Enabled

Typical Duration

10 Seconds

Dash Lamps

CEL

Engine Reaction

None

Verification

Engine Idle (One Minute)

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All information subject to change without notice.

Copyright © 2016 DETROIT DIESEL CORPORATION 05 17-16

05 17-16

WARNING: ENGINE EXHAUST
To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area.
Engine exhaust is toxic.

CAUTION: ELECTRICAL SHOCK
To avoid injury from electrical shock, use care when connecting battery cables. The magnetic
switch studs are at battery voltage.

WARNING: PERSONAL INJURY
To avoid injury, never remove any engine component while the engine is running.

Check as follows:
1. Check for multiple battery voltage faults. Are there other ECU voltage fault codes present?
a. Yes; Go to step 2.
b. No; Go to step 6.
2. Check the condition of the alternator drive belt and replace, if required. Is fault still active?
a. Yes; Go to step 3.
b. No; verify repairs.
3. Check for loose alternator mounting and retighten or repair, as required. Is fault still active?
a. Yes; Go to step 4.
b. No; verify repairs.
4. Check for proper alternator operation and repair or replace, as required. Is fault still active?
a. Yes; Go to step 5.
b. No; erase fault code memory.
5. Check the condition of the battery; does it hold the charge? Replace if required. Is fault still active?
a. Yes; Go to step 6.
b. No; verify repairs.
6. Turn the ignition OFF.
7. Disconnect the ACM 21-pin connector. Inspect the harness for bent, spread, or corroded pins. Is damage found?
a. Yes; repair as necessary.
b. No; Go to step 8.
8. Measure the resistance of the Aftertreatment Control Module (ACM) ground circuits located on pins 3, 5, 6, 8, and 9
of the ACM 21-pin connector to battery ground. Is the resistance less than five ohms?
a. Yes; Go to step 9.
b. No; repair the wire(s) with the high resistance reading.
9. Turn the ignition ON (key ON, engine OFF).
10. Measure the battery voltage of the individual wires in the power circuits at pins 11, 12, 14, 15, and 18 on the ACM 21pin connector. Is battery voltage less than 10.5 volts?
a. Yes; repair the circuit(s) in question.
b. No; reconnect ACM 21-pin connector. Go to step 11.
11. Connect DiagnosticLink ®. Monitor (chart) the following parameters.
• ASL: Ignition Switch Voltage
• ASL: Main Battery Voltage
• AAS: Battery Voltage
• ASL: Battery Voltage
12. Wiggle test the harness, looking for abnormal voltage spikes. Is a voltage spike detected?

All information subject to change without notice.

05 17-16

Copyright © 2016 DETROIT DIESEL CORPORATION

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2 SPN 168/FMI 1 - GHG17
a. Yes; isolate that section of harness and inspect for wire chaffing, corrosion, improper connections or physical
damage and repair as necessary.
b. No; Go to step 13.
13. Using DiagnosticLink, clear codes. Does fault return?
a. Yes; install a test ACM and retest.
b. No; verify repairs and release vehicle.

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All information subject to change without notice.

Copyright © 2016 DETROIT DIESEL CORPORATION 05 17-16