Service Bulletin

FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

> Century Class Conventional
> Argosy COE
Cargo
> Columbia

> 122SD and Coronado
> Business Class M2
> Cascadia
> 108SD/114SD

Starter Path Check — EPA07 Engines ONLY
Amp Clamp and DMM Location:
Engine:
5a. Amp clamp around POS starter cable for starter draw.
Crank engine, under 30 sec.
5b. DMM on POS battery pack cable and POS starter post.
Crank engine, under 30 sec.
5c. DMM on NEG battery pack cable and NEG starter post.
Crank engine, under 30 sec.
Combine the voltage from the positive and negative cable drop tests.

Rec
Value

Accept
Value

+
+
=

N/A
Less than
max V drop
in table.

On crank, the starter cable is likely to have between 400
and 1000 amps of current running through it. This test uses
an amp clamp to view the crank amperage. The allowed
voltage drop depends on the crank amperage.
NOTE: This test may require an assistant.
Starter Path Check – Checks 5a, 5b, and 5c – EPA07
only
5a - Measuring crank amperage with amp clamp
Place an amp clamp on the positive starter cable, set it to
read current between 400 and 1000 amps, and zero it. See
Fig. 9.
5b - Starter positive cable drop test
5b.1 Clip the DMM to the threaded portion of the positive
post on the starter and the positive lead base of one of the
batteries.
5b.2 Crank the engine. After the voltage reading normalizes
(about 2 to 3 seconds), but before the engine starts, record
the voltage drop shown on the DMM.
06/24/2013

f151191

Fig. 9, Measure the crank amperage with an amp clamp on
IMPORTANT: Do not crank for longer than 30 seconds.
Allow the starter to cool for 2 minutes between crank events. the positive starter cable during crank.
5c - Starter negative cable drop test
5c.1 Clip the DMM to the threaded portion of the negative
post on the starter and the negative lead base of one of the
batteries.
5c.2 Crank the engine. After the voltage reading normalizes
(about 2-3 seconds), but before the engine starts, record the
voltage drop shown on the DMM.
Combine the voltage drop of the positive and negative cable
drop tests. Look up the crank amperage recorded using
Table 2; total voltage drop from the two tests should not
exceed the value given. If total voltage drop is greater than
the allowed voltage, go to Check 6, then test voltage drop
again. If total drop is within the allowed value, go to Check
6 but do not retest voltage drop.

Page 6

Amps

Max. Acceptable
Combined V Drop

375-449

0.6

450-549

0.7

550-624

0.8

625-724

0.9

725-799

1.0

800-874

1.1

875-974

1.2

975-1025

1.3

Table 2, Max. Acceptable Combined V Drop by
Amperage

Freightliner Service Bulletin, February 2014

Powernet Troubleshooting Guide: Batteries, Path, Alternator,
and Starter
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

6.

> Century Class Conventional
> Argosy COE
Cargo
> Columbia

> 122SD and Coronado
> Business Class M2
> Cascadia
> 108SD/114SD

54-278
Freightliner
Service Bulletin

Check all cable connections for corrosion and torque. Repair or replace if needed, then test again.

Check 6 – Check all cable connections for corrosion
and torque. See Fig. 10 and Fig. 11. Repair or replace if
needed, then test again.
Loose connections can cause intermittent problems as well
as higher resistance, and are likely to have corrosion. Most
battery labels will specify the torque value; if the torque
value cannot be found, use 10 to 15 lbf·ft (13 to 20 N·m).

06/24/2013

f151192

Fig. 10, Check the positive post on the starter solenoid for
loose cables and corrosion.

06/24/2013

f151194

Fig. 11, Check the battery connections for looseness and
corrosion. Check the torque on the connections.

Freightliner Service Bulletin, February 2014

Page 7

54-278

Powernet Troubleshooting Guide: Batteries, Path, Alternator,
and Starter

Freightliner
Service Bulletin

FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

> Century Class Conventional
> Argosy COE
Cargo
> Columbia

ADDITIONAL BATTERY LOADS CHECK
Key-off Loads
7. Key off, Load Disconnect Switch set to "Off" (if equipped). Wait 3 minutes for all loads to stop.
Set amp clamp to a lower range setting. Zero amp clamp away from the vehicle.
For each POS cable leaving batt pack, clamp the cable and record the amperage.
If more than 1.0 amp, find sources of drain and remedy as needed.

> 122SD and Coronado
> Business Class M2
> Cascadia
> 108SD/114SD

Rec
Value
+
+
+
=

Accept
Value
Add amps.
Total must
be less
than 1 amp.

Check 7 – Detail, Key-off Loads Check
A key-off load is an electrical load that still draws current
from the batteries when the ignition remains off, and in some
cases, when the load disconnect switch is off. Some devices, such as the engine controller, the antilock braking system (ABS), and the radio memory, are intended to draw a
very low current continuously. In long-term parking situations, however, these drains may discharge the batteries
enough to cause a no-start condition. Key-off loads tend to
be measured in milliamps (mA).
7.1 Set the Load Disconnect Switch to "Off." Shut the door,
and wait 3 minutes after shutting the door for all "keepalives" (signals sent between devices) to turn off.
NOTE: On vehicles with a SAM module, the SAM will wake
up for a self-check after 30 minutes of inactivity, then turn
off.
7.2 Zero the amp clamp away from the vehicle to ensure
that all battery draw—including "background" current—is
detected upon measurement. Similarly, the amp clamp
should be set to a lower, sensitive setting.
7.3 For each positive cable leaving the battery pack, clamp
the cable and record the amperage. See Fig. 12. Add the
amperages together. If the total is more than 1.0 amp, find
the sources of drain and remedy as needed.

06/24/2013

f151195

Fig. 12, After zeroing the amp clamp away from the
vehicle, measure the amperage in each positive cable
leaving the battery pack.

Finding Sources of Battery Drain
Pull fuses individually on the circuit with the highest draw
until the total combined amperage drops below 1.0 amp.
From there, find the component on that particular circuit
drawing the additional current. Repair or replace as needed.
NOTE: Opening and shutting doors will wake up system
keepalives. If a door is opened during the procedure, wait 3
minutes after closing the door before measuring draw.
NOTE: The LVD (low voltage disconnect) could be bypassed
by inverters or other aftermarket installed systems.

Page 8

Freightliner Service Bulletin, February 2014

Powernet Troubleshooting Guide: Batteries, Path, Alternator,
and Starter
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

> Century Class Conventional
> Argosy COE
Cargo
> Columbia

> 122SD and Coronado
> Business Class M2
> Cascadia
> 108SD/114SD

Freightliner
Service Bulletin

Rec
Value

Key-on Loads
8.

54-278

Amp clamp on POS alt cable. ENG at IDLE, turn on driver’s normal use loads.
If load is more than 80% rated amps, find sources of draw and/or upgrade alternator.
Retest after remedying.

Accept
Value
Total less
than 80%
rated amps.

Check 8 – Key-On Loads Check
This test looks at the "normal use" loads of the vehicle during normal operation conditions by measuring draw at
the alternator positive cable. "Normal use" should include high beams, radio, blower, and additional driver
accessories.
At idle, the total load should not be above 80% of the alternator’s rated output (e.g. 270 amps x .80 = 216
amps). See Table 2 for 80% load by alternator amperage rating. If the normal use load is higher, then a number
of related issues can be at play that are outside the scope of this troubleshooting topic. These might include
high-draw loads, and circuit voltage drop (from corrosion, looseness, or damage).

Amp
Max. Load
135
108
160
128
185
148
200
160
240
192
270
216
275
220
Table 3, Max. Acceptable Key-on Load by Alternator
Amperage Rating

If all systems are functioning properly, but the normal use load exceeds the alternator rating, either a higher
rated alternator should be installed, or non-essential high-draw loads should be permanently removed from the
system.

Freightliner Service Bulletin, February 2014

Page 9

54-278
Freightliner
Service Bulletin

Powernet Troubleshooting Guide: Batteries, Path, Alternator,
and Starter
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

> Century Class Conventional
> Argosy COE
Cargo
> Columbia

CHARGING SYSTEM CHECK - ALTERNATOR
9a. DMM on POS and NEG of batt pack. (Undercharge check)
9b. DMM on POS and NEG of batt pack. (Overcharge check)
Carbon Pile:
DMM:
10. POS and NEG of batt pack. POS and NEG of batt pack.

> 122SD and Coronado
> Business Class M2
> Cascadia
> 108SD/114SD

Key
Engine
Position
IDLE
KEY ON
2000 RPM KEY ON

Carbon
Rec
Pile
Value
NO LOAD
NO LOAD
70% of
2000 RPM KEY ON alt rated

Accept
Value
13-15.5 V
13-15.5 V
Within 1 V
of above

Checks 9a and 9b – Under and Overcharge Checks
9.1 With a DMM, probe any battery in the primary battery
pack at the negative and positive battery posts. With the engine running at idle and no loads turned on, record the voltage at the pack.
9.2 With the engine running at 2000 RPM and no loads
turned on, record the voltage at the pack.
In both cases, the voltage should be above 13 V, and higher
than it was before starting the engine. If not, the alternator is
undercharging, and should be replaced.
If the voltage reads above 15.5 V, the alternator is overcharging the batteries. Check the remote sense circuit before condemning the alternator.

06/24/2013

f151197

Fig. 13, Use an amp clamp around the positive alternator
cable to measure the draw of the carbon pile.

Check 10 – 70% of Rated Output Check
10.1 With a DMM, probe any battery in the primary battery
pack at the negative and positive battery posts.
10.2 Clamp the carbon pile to the positive and negative battery pack leads.
10.3 Place an amp clamp around the positive alternator
cable and zero the clamp. The amp clamp will be used to
measure the draw of the carbon pile. See Fig. 13.
10.4 With the engine running at 2000 rpm, adjust the carbon
pile until the amp clamp reads 70% of the alternator rated
amperage (e.g. 270 amps x .70 = 189 amps). See Table 4.
With this load applied, record the voltage at the battery
pack.
While the load is applied, the voltage reading on the DMM
should not drop more than 1.0 V below the reading in step
9b (the 2000 RPM, no load condition). If the voltage difference is more than 1.0 V, replace the alternator, then perform
tests 9a and 9b again to verify the repair.
IMPORTANT: The voltage will drop if the carbon pile is drawing more than 70% of the alternator rating. Do not replace if
a low voltage reading was seen with a load above 70%. Instead, test again with 70% of the alternator’s rated load.

Page 10

Alternator
Rating (Amp)

Use Carbon
Pile Draw
(Amp)

135

95

160

112

185

130

200

140

240

168

270

189

275

193