FG00066
PARTS-SERVICE
September 20, 1996
E30-50FR
GRAM
Subject: System Controller Power Source
When the System Controller loses power, the amplifiers may be damaged. I the controller loses power
because the fuse failed or is disconnected while the main power contactor remains closed, the amplifiers
may receive uncontrolled current.
The following procedure should be conducted to change the fuse wiring around the main power
contactor.
1. Disconnect the battery and discharge the capacitor bank.
Note: Discharge the capacitor bank by turning the key on after disconnecting the battery. The
display will come on and then go out, indicating the capacitor bank is discharged.
2. Remove the top cover.
3. Determine which wiring scheme the truck has:
Type A: There is an in-line fuse holder from the main harness connected to the positive
(right) bus bar of the contactor, and a fuse block mounted on the contactor frame (see
Figure A - Before on page 2).
Type B1/B2: There is an in-line fuse holder from the main harness connected to the positive
(right) bus bar of the contactor, but no fuse block mounted to the contactor frame (see
Figures B1 and B2 - Before on pages 3 and 4).
Type C: There is no in-line fuse holder connected to the contactor and there is no fuse block
mounted on the contactor frame ( although there are two fuse blocks above the
contactor (see Figure C on page 5).
If the truck has a Type A wiring (see Figure A on page 2), perform the following procedure:
Al. Using a 1/2" wrench, remove the red wire with the in-line fuse holder from the B+ bus bar of the
main power contactor. Reattach the two cables and the wire coming from the right side of the
fuse on the contactor frame to the B+ bus bar of the contactor. Do not overtighten the nut -
overtightening may bend the bus bar.
A2.Cut off the fused wire (Do not discard the fuse if it is 15 amp, it will be used in Step A7) and
butt-splice a 12 inch piece of 18 gauge black wire in its place.
A3.Crimp an insulated male/female spade terminal to the other end of this wire.
A4.Disconnect the short wire coming from the left side of the fuse mounted on the contactor frame at
the top terminal of the contactor coil
A5.Plug the male/female terminal of the new wire onto the top terminal of the contactor coil.
...continued
We reserve the right to make changes in design or add improvements without incur-
ring the obligation to make such changes in equipment previously manufactured.
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A6. Plug the wire from Step A4 into the male terminal of the male/female terminal.
A7. Remove the 1 amp fuse from the fuse holder mounted on the contactor frame and install a 15 amp fuse.
A8. Ensure that none of the wires can interfere with or be abraded by the contactor tips.
A9. Connect the battery and turn the truck on to test.
Before
After
Figure A
Type A Wiring Scheme (In-line fuse holder and fuse block on contactor frame.)
...continued
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If the truck has Type B1 or Type B2 wiring, perform the followmg procedure (refer to Figure B 1
and Figure B2):
Note: Start with Step B3 if your truck has a wirmg scheme like Figure B1 below.
B1. Remove the short jumper wire between the two fuses above the contactor.
B2. Crimp two ring terminals on a 5 inch piece of 18 gauge wire. One terminal must be 5/16" and
will be connected to the positive bus bar of the contactor. Using the appropriate ring terminal,
connect the other end to the left side of the lower fuse block above the contactor (see Figure
B2 - After on page 4).
B3. Using a 1/2" wrench, remove the red wire with the in-line fuse holder from the B+ bus bar of
the main power contactor. Reattach the two cables and the wire (from Step B2) coming from
the left side of the lower fuse above the contactor to the B+ bus bar of the contactor. Do not
overtighten the nut - overtightening may bend the bus bar.
B4. Cut off the wire with the in-line fuse holder and butt-splice a 12 inch piece of 18 gauge black
wire in its place.
B5. Crimp an insulated ring terminal to the other end of this wire.
B6. Connect th new wire to the right side of the lower fuse block above the contactor. Ensure this is
a 15 amp fuse, if it is not, replace it with a 15 amp fuse.
B7. Ensure that none of the wires can interfere with or be abraded by the contactor tips.
B8. Connect the battery and turn the truck on to test.
Before
Figure B1
Type B1 Wiring Scheme (With this wiring scheme, Steps B1 and B2 are not necessary.)
...continued
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Before
After
Figure B2
Type B2 Wiring Scheme (In-line fuse holder but no fuse block on contactor frame.)
...continued
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If the truck has a Type C wiring (see Figure C below), no modifications are necessary.
Figure C
Type C Wiring Scheme (No in-line fuse holder or fuse block on contactor frame.)