BULLETIN NUMBER:
SB20-H-001

IMPORTANT SERVICE
INFORMATION FOR:
 SERVICE MANAGER
 SERVICE ADVISOR
 TECHNICIAN
 PARTS DEPARTMENT
 WARRANTY PERSONNEL

ISSUE DATE:
FEBRUARY 2020
GROUP:
BRAKES

DTC P0027 AIR DRYER LINE REROUTING
AFFECTED VEHICLES


2018-2019 MY Isuzu FTR vehicles
Produced prior to January 2, 2019
CONDITION

Some customers may complain about an illuminated check engine light setting shortly
after starting the engine. If the reason for the check engine light illuminating is DTC
P0027, the most likely cause is low brake air pressure.
DTC P0027 may set when the brake air pressure is very low or at 0 psi at the time the
vehicle is started. The brake air pressure can be depleted (resulting in low or 0 psi) after
the air system has been serviced or the vehicle has been stored for a long period of
time.
If DTC P0027 continues to set even though there are no air system leaks that may be
quickly depleting the air supply or causing delays in the buildup of air pressure and the
exhaust brake is functioning properly, follow the service procedure in this bulletin to
reroute air dryer lines for improved air support to the exhaust brake.
SERVICE PROCEDURE

Front of Vehicle
Bottom View

Before

After

Figure 1 – Before and After Rerouting Air Dryer Lines
1. Place the vehicle in park, apply the parking brake, and turn engine off.

2. Drain air from the air brake system (see Figure 2) by pulling the lanyards, as
shown in Figure 3, on the primary and secondary air reservoirs until system is
completely empty.

C

B

A

Figure 2
A. Primary reservoir
B. Secondary reservoir
C. Air Dryer
Secondary

Primary

Figure 3
A. Arrow points to lanyard.
B. Circle shows reservoir drain valve.
3. Remove four (4) tie straps holding the auxiliary and secondary air lines in place.
(See Figure 4.)

2

Bottom View

B

A
Front of Vehicle
Figure 4
A. Secondary air line
B. Auxiliary air line

4. Disconnect the ½” line from “22 SEC” connector at the air dryer (see Figure 5)
and the other end from the secondary reservoir.
5. Disconnect one end of the 3/8” exhaust brake air line from “23 AUX” connector
at the air dryer connector. (See Figure 5.)

3

23
AUX2

22
SEC
Figure 5

6. Remove the two connectors from air dryer located at ports “22 SEC” and “23
AUX” and discard. (See Figure 6.)

22
SEC

23
AUX2

Figure 6
7. Apply Teflon tape onto threads of the new, straight 3/8 x ¼ PTC connector.
Install into the air dryer port 22 SEC and torque to 13.5±2.7 Nm (10±2 lb·ft).
(See Figure 7, “A”.)

4

8. Apply Teflon tape onto threads of the new, 90ᵒ swivel, ½ x ¼ PTC connector.
Install into the air dryer port 23 AUX and torque to 13.5±2.7 Nm (10±2 lb·ft).
(See Figure 7, “B”.)
CAUTION: When putting Teflon tape onto the connectors do not wrap over the
port openings as this may cause component damage and/or brake system
malfunction could occur.

A

B

Figure 7
9. With a marker, mark and cut the ½” line to 380mm as measured from end that
connects to reservoir. (See Figures 8 and 9.)

Figure 8

5

Figure 9
10. With a marker, draw a new insertion depth line ending 24.4mm (1 inch) from
cut end. (See Figure 10.)

Figure 10
11. With a marker, mark and cut the 3/8 inch line to 400mm as measured from end
that connects to the dryer. (See Figures 11 and 12.)

Figure 11 – Dryer harness disconnected solely for purposes of this photo
6

Figure 12
12. With a marker, draw a new insertion depth line ending 19.8 mm (25/32 inch)
from cut end.
13. Insert the ½” line with cut end into swivel connector at port 23 AUX on the air
dryer and other end into reservoir. (See Figure 13.)
14. Insert the 3/8” line into air dryer connector at port 22 SEC. (See Figure 13.)

1/2 inch
line

3/8 inch
line

Bottom View
7

Figure 13
NOTE: Ensure lines are firmly inserted into connectors up to insertion marks to
prevent air leakage.
15. Install tie straps in locations shown in Figure 14.

Tie Straps

Bottom View
Figure 14
16. Move the secondary air reservoir manual drain lanyard to new location by
removing the lanyard ring from current mounting location. (See Figure 15.)
17. Attach the lanyard ring to the new p-clip. Remove the nut from the new
location. Install p-clip on stud, install nut, and torque to 22.8±6.8 Nm (16.8±5 ftlb) as shown in Figure 16.

8

Lanyard
Ring

Figure 15

New lanyard
mounting location

Figure 16

18. Using brake cleaner, clean the locations where new identification labels will be
mounted, as shown by red rectangles in Figures 17 and 18.
19. Affix new labels to air dryer. Place “SEC” label over “AUX2” marking. (See
Figure 17.) Place “AUX2” label over “SEC” marking. (See Figure 18.)

Figure 17 - “SEC” label

Figure 18 - “AUX2” label

20. Refill air system and check for leaks. If a leak is found, ensure air lines are fully
inserted into connectors and confirm there is no more leakage.
PARTS INFORMATION
The following new parts are available from AIPDN:
9

Part Number
8-98320-358-0
8-97548-534-0
8-11509-087-0
0-95235-866-0
2-90LB0-001-0
2-90LB0-000-0

Description
FITTING ASM; MALE CONNECTOR 3/8
PTC X ¼ NPT
FITTING ASM; MALE CONNECTOR 1/2
PTC X ¼ NPT
TIE STRAP
CLIP; PLATE, TYPE A3, W/COATING
AUX2 LABEL
SEC LABEL

Qty
1
1
2
1
1
1

WARRANTY INFORMATION
Labor Operation Code
H2370

Description
AIR DRYER LINE REROUTING

Labor Time
0.5

10