Hummer H1 Service Manual page 929

12-152 Electrical System
DISPLAY IS INOPERATIVE, NO SOUND FROM ANY SPEAKER
STEP ACTION
1 Disconnect connector C56.
Turn the ignition switch to the "Run"
position.
With a DVOM, measure voltage between
terminal "7" and ground G4.
2 With a DVOM, measure the voltage at
connector C56 between terminal "7" and
terminal "8".
3 With a DVOM measure the voltage at
connector C56 between terminal "4" and
terminal "8".
4 Check for a poor connection at the radio.
If OK, service radio.
ACTION
1 Turn the ignition switch to the "off" position.
Disconnect connectors C56, C57 and C58.
With a DVOM, measure the resistance at
the connector C56 between speaker +
and - circuits (see schematics).
2 With a DVOM, measure the resistance at
the speaker connection from terminal
"A" to terminal "B".
3 With a DVOM measure the resistance at
the radio connector of the speaker + and -
circuits to ground.
4 Check for poor connections at radio or
speaker.
If OK, service radio.
3-1-01
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NO SOUND FROM ONE SPEAKER (DELCO STANDARD)
CHART #1
VALUE(S) YES
+12v Go to step 2.
+12v Go to step 3.
+12v Go to step 4.
CHART #2
VALUE(S) YES
4Ω Go to step 3.
4Ω Repair open or short circuit
in speaker + and - circuits.
Infinite Go to step 4.
resistance.
NO
Repair the poor connection
or open the gray wire (CKT
476) between connector C56
terminal "7" and fuse 2H of
the interior fuse box.
Repair the poor connec-
tion or open in the black
wire (CKT 59) between
connector C56 terminal
"8" and ground G4.
Repair open in the red wire
(CKT 137) between connec-
tor C56 terminal 4 and fuse
4G of the interior fuse box.
NO
Go to step 2.
Replace speaker.
Repair short to ground in
speaker + or - circuit.
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