TROUBLE SHOOTING GUIDE Dual Fuel Tank Kit after Campaign TABLE OF CONTENTS SUBJECT

PAGE NUMBER

System Operation

2

Warning Light

2

Manifold Diagnostics

3, 4

Circuit Protection/ Fuel Manifold

5

No Power at Manifold w/ Selector Switch in Auxiliary

5

Verify Ground Wires

6

Gauge Inoperative w/ Selector Switch in Auxiliary

8

Gauge Inoperative w/ Selector Switch in Main

9

Gauge Inoperative w/ Selector in either Main or Auxiliary

9

Check Valve for Proper Operation

10

Cab Harness Diagram

11

Cab Harness Extension Diagram

12

Chassis Harness Diagram

13

Filter Maintenance

14

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

Page 1 of 14

TROUBLE SHOOTING GUIDE Diagnostic and Test Information System Operation Main tank Position: Fuel gauge monitors rear (Main) tank fuel level. Fuel Manifold is not powered (0 volts). Manifold normal (default) position is draw a nd return to rear (Main) fuel tank. Warning light will never illuminate in this position. Auxiliary position: Fuel gauge monitors side (Auxiliary) tank fuel level. Fuel Manifold is powered (12 volts). Dash warning light performs system check by turning on for 3-5 seconds. If system is OK then light will go out. Fuel manifold energized and now draws and returns fuel from the side (Auxiliary) fuel tank. Important: The Warning Light only activates when switched to the Auxiliary position. If the Warning Light remains “ON” in the Auxiliary position, the fuel manifold will only draw fuel from the main tank. The Selector switch must be switched back to main position to read main tank fuel level. Important: The fuel gauge only reads the selected fuel tank. System failure or warning light activation will not switch/modify fuel gauge reading from selected position. Warning Light

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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TROUBLE SHOOTING GUIDE Diagnostics The following diagnostics have been designed to assist technicians in repairing the updated (after campaign) Isuzu Dual Fuel Tank System. It is important for the repairing technician to note the behavior of the new dual fuel tank warning light. This light is the key to these diagnostics. It is important to note when the warning lamp cycles “ON” and “OFF” to accurately understanding how the dual fuel tank system is functioning. After confirming the customer’s complaint and accurately noting the warning lamp operation, follow the appropriate diagnostic to assist in the repair of this system.

Warning light does not come "On" when switched to Auxiliary.

When the dual fuel tank selector auxiliary position is selected the warning lamp should illuminate temporarily during the system check. This diagnostic will assist in diagnosing an inoperative light during this event. Step

Description

Value

Yes

No

1

Is voltage present at 7.5amp fuse?

12 volts

Go to step 2

Repair/replace power source/Fuse and recheck circuit.

2

With the selector switched to Auxiliary, check red wires pins 1,2 and 3 at the 6 pin manifold connector. Is voltage present at manifold connection?

12 volts

Go to step 3

Repair Harness fault between fuse and manifold connector and recheck circuit.

3

Is voltage present at manifold ground?

0 volts

Repair ground and retest circuit.

Go to step 4

4

When the auxiliary position is selected is voltage temporarily present to Warning lamp circuit at the manifold?

12 volts

Go to step 5

Internal fault of Fuel manifold. Replace fuel manifold.

5

When the auxiliary position is selected is voltage temporarily present to Warning lamp circuit at the Warning Lamp?

12 volts

Go to step 6

Repair harness connection between manifold and Warning lamp.

6

When the auxiliary position is selected is voltage temporarily present at the Warning lamp circuit ground?

0 volts

Repair ground and retest circuit.

Go to step 7

7

Check LED connection and resistance.

__

Repair or Replace LED as necessary.

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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TROUBLE SHOOTING GUIDE Warning light does not go "Off" when STARTED in the Auxiliary position When the dual fuel tank selector auxiliary position is selected and the vehicle is STARTED, the warning lamp should illuminate temporarily during the system check and then go “OFF”. This diagnostic will assist in diagnosing when the warning light does not go “Off”. Step

Description

Value

Yes

No

1

When the vehicle is started with the Auxiliary position selected does the warning light come “ON” and Stay “ON” after the engine is running?

Go to step 2

------

2

With the vehicle still running, change the selector switch from “Aux” to Main”. Does the warning light go “OFF”?

Go to step 3

Short to Power. Repair harness failure.

3

With the vehicle still running, change the selector switch from “Main” to “Aux”. Does the warning light come back “ON” and stay “ON”?

Internal fault of Fuel manifold. Replace fuel manifold

Refer to Manifold protection circuit description. Change power circuit per below figure.

Step 3 Power circuit change Relocate Main power to solid Blue wire

Without Engine Protection System

With Engine Protection System

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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TROUBLE SHOOTING GUIDE Circuit Protection/ Campaign Manifold

In order to protect against abnormal fuel manifold operation, a circuit protection device has been added to the updated manifold. The circuit protection measures the current going through each coil. This is done by measuring the voltage drop across resistors. If the voltage drop across each resistor is in a certain range then the circuit stays active. The maximum and minimum voltage is determined by a window comparator portion of the circuit. If the voltage drop across one or more current sensing resistors is above or below the maximum or minimum, then power will be removed from all three coils and the warning light will be illuminated. Power must be removed from the circuit in order for the circuit to reset itself.

There is no power at the Manifold when the Selector Switch is in the Auxiliary Position NOTE: - Make sure that all the connectors are connected properly between the selector switch cab harness (Figure 2) and the cab harness extension and the chassis harness and the fuel manifold. APPROXIMATE LOCATION OF RED WIRE, IGNITION POWER CONNECTION OF ENGINE PROTECTION SYSTEM OR CRUISE CONTROL. SWITCH HARNESS INTERCONNECTION HARNESS

CHASSIS HARNESS

B67

GROMMET/PUTTY

Figure 2

Figure 3

• Check the interconnection harness, make sure the harness is connected properly between the B-67 connections. (See Figure 3). Using a voltmeter, verify that when the ignition key is turned to the ON position you have +12 volts at the switch harness power connector. If OK, go to Step 2. • Check the fuse in the cab harness, if blown, verify that the RED wire has good continuity and there is no short to the ground. Using a continuity meter look for a short to ground between the fuse Pin A and the switch harness connector Pin G. Also check from the cab extension harness Pin G to the end of the harness Pin G and from the chassis harness Pin G to the manifold connector Pin A, B & C. Install new fuse and repair any short found appropriately. Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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TROUBLE SHOOTING GUIDE How to Verify the Ground Wires of the System (See Figure 4 & 5) The fuel tank harness has two (2) ground wires. One is in the cab connected to the TCM mounting bracket and the other is located beside the manifold. Make sure that both ground wires are secured properly and that they have a clean and reliable source. Using a continuity meter, verify the ground wire from the cab ground to the Pin B o f the switch harness connector. From the front of the cab extension harness Pin B to the end of the extension harness Pin B and from the chassis harness Pin B to the manifold connector Pin D, E & F. If no continuity or very high resistance, repair appropriately.

HARNESS GROUND FROM ITEM

Figure 4

FIGURE 3 (A/T GROUND WIRE) TO CAB SWITCH

Figure 5

TRANSMISSION CROSSMEMBER

TO AUX. TANK

GAUGE CONNECTION (RIGHT FRAME RAIL)

GROUND TERMINAL MANIFOLD MOUNTED INSIDE LEFT FRAME RAIL

TO MAIN TANK

For the next Three (3) diagnostic and test procedures refer to Figures 5 - 10

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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TROUBLE SHOOTING GUIDE APPROXIMATE LOCATION OF RED WIRE, IGNITION POWER CONNECTION OF ENGINE PROTECTION SYSTEM OR CRUISE CONTROL. SWITCH HARNESS 2

3

INTERCONNECTION HARNESS

CHASSIS HARNESS 4

B67

Figure 6

GROMMET/PUTTY 5

RETAINING CLIPS RETURN LINE SUPPLY LINE

RETAINING CLIPS RETURN LINE

RETURN LINE

SUPPLY LINE

SUPPLY LINE

BRAKE LINE (DO NOT CUT)

CHASSIS HARNESS TO AUX. TANK CHASSIS EXTENSION HARNESS TO CAB SWITCH

CHASSIS HARNESS TO MAIN TANK

Figure 7

CHASSIS HARNESS TO GAUGE HARNESS RIGHT FRAME RAIL

TRANSMISSION CROSSMEMBER

GAUGE CONNECTION (RIGHT FRAME RAIL)

Figure 8

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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TROUBLE SHOOTING GUIDE AUX. TANK

BLACK CONNECTORS

FROM CHASSIS HARNESS

FRONT

WHITE CONNECTORS

DIESEL FUEL ONLY

Figure 9

MA IN F UE LT AN K

Figure 10

RE AR TA NK SE EX FR NDIN IST OM ING G NE UNIT CO REA W MA CON NN R T NIF EC AN N TIO K S OL ECT D ION N ( EN PLU DIN GG G U ED NIT )

Fuel Gauge & Low Fuel Warning Light Inoperative when Selector Switch is in Auxiliary Position Make sure that all the connectors are connected properly between the selector switch cab harness and the cab harness extension and the chassis harness and the auxiliary fuel harness connector and the gauge harness connector. If OK, using a continuity meter, verify the LT. BROWN, black wire from the selector switch connector all the way to the fuel sender connector on the auxiliary tank. If OK, verify the YELLOW/black wire from the selector switch connector all the way to the fuel sender connector on the auxiliary tank. If OK, verify BLACK wire for

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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TROUBLE SHOOTING GUIDE Continuity to the ground from the selector switch connector all the way to the fuel sender connector on the auxiliary tank. Then verify for continuity the YELLOW/red and Lt. BROWN/red wires from the selector switch connector all the way to the fuel gauge connector located inside the right frame rail across the transmission. If OK, verify BLACK wire at the Fuel gauge connector located inside the right frame rail across the transmission. If OK, verify the tank sender, dash gauge and factory wiring per Isuzu Service Manual. Fuel Gauge Inoperative when Selector Switch is in the Main Position Make sure that all the connectors are connected properly between the selector switch cab harness and the cab harness extension and the chassis harness and the auxiliary fuel harness connector and the gauge harness connector. If OK using a continuity meter, verify the Lt. BROWN wire from the selector switch connector all the way to the fuel sender connector on the auxiliary tank. If OK, verify the YELLOW wire from the selector switch connector all the way to the fuel sender connector on the main tank. If OK, verify BLACK wire for continuity on the ground of the selector switch connector all the way to the fuel sender connector on the main tank. Then verify for continuity the YELLOW/red and Lt. BROWN/red wires from the selector switch connector all the way to the fuel gauge connector located inside the right frame rail across the transmission. If OK, verify BLACK wire at the F uel gauge connector located inside the right frame rail across the transmission. If OK, verify the tank sender, dash gauge and factory wiring per Isuzu Service Manual. Fuel Gauge Indicator is not Working when the Selector Switch is either in the Main or Auxiliary Position. Make sure all connector are connected properly between the selector switch cab harness and the cab harness extension, the chassis harness and the auxiliary fuel harness connector, and the main fuel harness interconnection and the gauge harness connector. If you did both the last two tests and everything is OK, then the gauge in the instrument panel maybe defective. Refer to the Isuzu Service Manual or the nearest Isuzu Dealer.

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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AUX

MAIN

AUX

MAIN

SWITCH TO AUX

AUXILIARY TANK

MAIN TANK NO RETURN AUXILIARY TANK AUXILIARY TANK MAIN TANK

NO SUPPLY MAIN TANK MAIN TANK AUXILIARY TANK

VALVE 2 MALFUNCTION

VALVE 3 MALFUNCTION

VALVE 2 & 3 MALFUNCTION

VALVE 1 & 3 MALFUNCTION

AUXILIARY TANK

RETURN TO:

AUXILIARY TANK

AUXILIARY TANK

SUPPLY FROM:

VALVE 1 MALFUNCTION

MALFUNCTION

AUXILIARY TANK

RETURN TO:

VALVE 3 MAIN TANK SUPPLY

PROPER OPERATION

RESULT:

SYSTEM ERROR REPLACE VALVE 1 SYSTEM ERROR REPLACE VALVE 2 SYSTEM ERROR REPLACE VALVE 3 SYSTEM ERROR REPLACE VALVE 2 & 3 SYSTEM ERROR REPLACE VALVE 1 & 3

PROPER OPERATION

RESULT:

FAIL SAFE TO MAIN, SYSTEM OPERATES PROPERLY IN ANY SOLENOID FAILURE (SUPPLY TO MAIN, RETURN TO MAIN)

SWITCH TO MAIN

VALVE 2 AUX TANK SUPPLY

SUPPLY FROM:

VALVE 1 RETURN

CHECKING VALVES FOR PROPER OPERATION

TROUBLE SHOOTING GUIDE

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

Page 10 of 14

(LT. BRN/BLK)

A B C

D E F

G H J AUX

(BRN)

SW1

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch A B B D E F

C2 FB C1 C2 C2 C2

TO

C A D

G A

PIN

B

C1

E D F C G B H A WIRE INSERTION VIEW

RED RED RED LT.BROWN/BLACK LT.BROWN/RED BROWN

WIRE COLOR

A

AUX. SENDER GAUGE MAIN SENDER

NOTE VALVE (+V) IGNITION (+V) IGNITION (+V)

E = YELLOW F = YELLOW/BLACK G = RED H = YELLOW/RED

C2

CHECK FOR 12V POWER

SW1 G C2 F YELLOW/BLACK AUX. SENDER SW1 H C2 H YELLOW/RED GAUGE SW1 J C2 E YELLOW MAIN SENDER C2 B GT BLACK GROUND CHECK POINT TO POINT WIRE CONNECTIONS FOR CONTINUITY. CHECK FOR SHORTS AND SHORTS TO GROUND.

PIN

SW1 SW1 FB SW1 SW1 SW1

(BLK)

(RED)

FB

CHECK FOR BLOWN FUSE REPLACE WITH 7.5A FUSE ONLY

A

FROM

GT GROUND TERMINAL

REAR VIEW OF SWITCH SW1

(RED)

(RED)

D C B

AUX

MAIN

(LT. BRN/RED)

(YEL)

MAIN

(YEL/RED)

(YEL/BLK)

LOCATED IN VEHICLE CAB DRIVER SIDE

D = BROWN C = LT.BROWN/BLACK B = BLACK A = LT.BROWN/RED

b

a

TROUBLE SHOOTING GUIDE

Page 11 of 14

a

E F G H

AB C D

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch H G F E

WIRE INSERTION VIEW

A B C D

H G F E

12

34

A = LT.BROWN/RED H = YELLOW/RED B = BLACK G = RED C = LT.BROWN/BLACK F = YELLOW/BLACK D = BROWN E = YELLOW

c

VEHICLE POWER

CHECK POINT TO POINT WIRE CONNECTIONS FOR CONTINUITY. CHECK FOR SHORTS AND SHORTS TO GROUND.

E = YELLOW F = YELLOW/BLACK G = RED H = YELLOW/RED

WIRE INSERTION VIEW

D C B A

CAB HARNESS EXTENSION

LOCATED DRIVER SIDE FRAME RAIL

12V POWER

BLK/YEL BLU BLK/WHT WHT/BLK CAB HARNESS

D = BROWN C = LT.BROWN/BLACK B = BLACK A = LT.BROWN/RED

b

RED

VEHICLE POWER

LOCATED IN VEHICLE CAB DRIVER SIDE

1 2

3 4

TROUBLE SHOOTING GUIDE

Page 12 of 14

c

C F B G A H

D E

BLACK

WIRE INSERTION VIEW

AUX. TANK

YELLOW/BLACK

RED

RED

RED

BLACK

BLACK

BLACK

BLACK

MANIFOLD

A F B E C D

F = BLACK E = BLACK D = BLACK

(BLK)(GRD)

TO MANIFOLD

A = RED B = RED C = RED

GROUND TERMINAL

YELLOW

BLACK

WIRE INSERTION VIEW BROWN

TO GAUGE HARNESS

LT. BROWN/RED

BLACK

YELLOW/RED

LOCATED DRIVER SIDE FRAME RAIL

CHASSIS HARNESS

CHECK POINT TO POINT WIRE CONNECTIONS FOR CONTINUITY. CHECK FOR SHORTS AND SHORTS TO GROUND.

TO AUXILIARY (SIDE) TANK

(+V) SPLICE LOCATION (SEE DETAIL ABOVE)

+V SPLICE

COMMON SPLICE

GAUGE

LT.BROWN/BLACK

COMMON SPLICE LOCATION (SEE DETAIL ABOVE)

RED

BLACK

BLACK

BLACK

BLACK

SPLICE DETAILS

TO MAIN (REAR) TANK

TROUBLE SHOOTING GUIDE

REAR TANK

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

Page 13 of 14

TROUBLE SHOOTING GUIDE Fuel Manifold Fuel Filter Maintenance

The Dual Fuel Tank system is equipped with two fuel filters. These filters are used to protect the manifold assembly from large debris that may enter from the fuel tanks. These filters are recommended to be replaced every 13,000 miles of operation.

Rev # D2, Date:10/01/06 Production Description: Dual Fuel Tank w/ Selector Switch

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