Power Mirrors — GMC Sonoma Syclone (1991-1992)

DESCRIPTION & OPERATION

CAUTION

When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

Voltage is supplied to the Power Mirror Switch at all times through the HORN/DM Fuse (20-amp) and the ORN (140) wire. Ground is provided through the BLK (150) wire and the Busbar Ground.

Rotating the Power Mirror Switch fully clockwise allows for control of the right hand mirror. Rotating the switch fully counterclockwise allows for control of the left mirror.

With the switch set for the left mirror, moving the switch handle to the left, connects the LT BLU (82) wire to the BLK (150) wire and the WHT (81) wire to the ORN (140) wire. The mirror will then move to the left, moving the switch handle to the right reverses polarity to the mirror motor and the mirror moves to the right.

Moving the switch handle up connects the LT BLU (82) wire to the ORN (140) and the YEL (88) wire to the BLK (150) wire. The mirror will then move up, moving the switch handle down reverses the polarity to the motor and the mirror moves down.

COMPONENT LOCATIONS

Component	Location
Busbar Ground	Left Side Of Instrument Panel (Scheme 1)
Fuse Block	Left Side Of Instrument Panel (Scheme 2)
Power Mirror	In Respective Door (Scheme 3)
Power Mirror Switch	Lower Right Hand Side Of Instrument Cluster (Scheme 3)
C342	Behind Center Of Instrument Panel (Scheme 2)
C345	Right Hand Cowl Side Panel (Scheme 2)
C346	Left Cowl Side Panel (Scheme 2)
C347	Behind Center Of Instrument Panel (Scheme 2)
C523	In Left Door (Scheme 3)
C623	In Right Hand Door (Scheme 3)
Grommet 304	Left Cowl Side Panel (Scheme 2)
Grommet 305	Right Hand Cowl Side Panel (Scheme 2)
Grommet 500	Left A Pillar (Scheme 2)
Grommet 600	Right Hand A Pillar (Scheme 2)
S320	Behind Left Side Of Instrument Panel (Scheme 2)
S321	Behind Right Hand Side Of Instrument Panel (Scheme 2)
S322	Behind Left Side Of Instrument Panel (Scheme 2)

Component Locations

Scheme 1

Scheme 2

Scheme 3

PRELIMINARY INSPECTION

Verify customer complaint by operating power mirror system. Visually inspect for obvious signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Replace as necessary. Inspect for loose or corroded connections, damaged wiring harnesses and/or switches.

Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary. If fault is not found, or fault still exists after any repair, diagnose by symptom. See SYMPTOM INDEX table under SYSTEM TESTS.

SYSTEM TESTS

Symptom	Perform Test
Power Mirrors Do Not Operate	A
Left Power Mirror Does Not Move Left & Right	B
Left Power Mirror Does Not Move Up & Down	C
Right Power Mirror Does Not Move Left & Right	D
Right Power Mirror Does Not Move Up & Down	E

SYMPTOM INDEX

If power mirrors do not operate at all (Scheme 4)

Scheme 4

Scheme 4: TEST A: POWER MIRRORS DO NOT OPERATE

TEST B: LEFT POWER MIRROR DOES NOT MOVE LEFT & RIGHT

If left power mirror does not move left and right (Scheme 5)

Scheme 5

Scheme 5: TEST B: LEFT POWER MIRROR DOES NOT MOVE LEFT & RIGHT

TEST C: LEFT POWER MIRROR DOES NOT MOVE UP & DOWN

If left power mirror does not move up and down (Scheme 6)

Scheme 6

Scheme 6: TEST C: LEFT POWER MIRROR DOES NOT MOVE UP & DOWN

TEST D: RIGHT POWER MIRROR DOES NOT MOVE LEFT & RIGHT

If right power mirror does not move left and right (Scheme 7)

Scheme 7

Scheme 7: TEST D: RIGHT POWER MIRROR DOES NOT MOVE LEFT & RIGHT

TEST E: RIGHT POWER MIRROR DOES NOT MOVE UP & DOWN

If right power mirror does not move up and down (Scheme 8)

Scheme 8

Scheme 8: TEST E: RIGHT POWER MIRROR DOES NOT MOVE UP & DOWN

REMOVAL & INSTALLATION