How do i test inoperative power mirrors on my 1998 GMC Sonoma? I have checked the fuse.it is ok.neither mirror works.has 12 volts to switch.

no symptoms posted (broke glass or ???) can we be on same page?
"how do I switch," verb switch , the mirror as switches inside, too.

please say what that word means. switch and the failure.
1: remove and replace with new.
2: move right to left and left to right side.

why would you do that #2
fold away mirrors/ Export only (this is usa forum so..)
these,NASA grade mirrors are very complex... not just glass and plastic. heaters ,motors, memory , etc.

the FSM cover all tests for the mirror, including scan data.

ill quote the FSM now , 8 steps (just 1 fail,not heat, not memory failure or fold failure)
ONE MIRROR INOPERATIVE
(1) If the one inoperative mirror is on the passenger
side, go to Step 2. If the one inoperative mirror is
on the driver side, go to Step 3.
(2) Check if the passenger front door will lock and
unlock using the power lock switch on the driver side
front door. If OK, go to Step 3. If not OK, go to Step 6.
(3) Disconnect and isolate the battery negative
cable. Remove the trim panel from the front door.
Disconnect the 12-way mirror wire harness connector
from the door wire harness connector.
(4) Using two jumper wires, test the mirror as
shown in the Mirror Test chart (Fig. 2). If the mirror
tests OK, go to Step 5. If the mirror does not test
OK, replace the faulty mirror.
(5) Disconnect the 12-way door wire harness connector
from the door module connector receptacle.
Check all of the circuits of the door wire harness
between the connector for the mirror and the connector
for the door module for opens or shorts. If all of
the circuits are OK, replace the faulty door module.
If any of the circuits are not OK, repair the open or
shorted circuit(s) as required.
(6) Use a DRB scan tool and the proper Diagnostic
Procedures manual to test and repair the faulty Programmable
Communications Interface (PCI) data bus
communication between the two door modules.

(bar stool answer) all cars. mostly
pull door skins
unplug motor conn.
unscrew mirror base from door.
extract mirror,

The first thing to do is have the mirror control switch tested, remove the switch from the door panel and proble it with a 12 volt test light as you operate the different functions of the p[ower side mirrors, if that is ok then replace the mirror.

check motor in mirrors for power,rember power travels battery+ to switch then to mirrors threw wires and conections there maybe a relay in the middel,then to earth threw panels or wires,if there algood maybe its the motors,,,but its rare to have both go at the same time

The mirrors require constant 12 volts power to keep the memory powered up, the fuse for this memory may be popped, suggest you check the fuse boxes for a bad fuse. If all the fuses are good then the control module is defective or the wiring is to it is.

It really helps if you post which engine you have and the 8th VIN digit. I ASSUME its a V6??? You should have 12 volts for 2 seconds on the gray wire (at the pump) when you turn the key on, If not, check the ECM/BATT fuse #9 20 amps, in the dash fuse panel. IF you do have power, then the relay is working and that is ok, If it does have power to the gray wire, then shuts off after 2 seconds thats normal. NOW while its running the fuel pump gets power THROUGH the OIL PRESSURE SWITCH. So get it running with your test wire, then disconnect your test wire. If it stalls out, then the oil pressure switch is either bad or disconnected.

1. check to see if there is a fuse for the mirrors and replace if bad.
2. check mirror control switch to make sure its working, also check contacts and make sure there clean, u can use a volt meter to see if there is power going to and from the switch, but if both mirrors are not working the rule of thumb is it must be something that would effect both and not just one mirror such as bad fuse bad switch or a break in the power line goting to the switch.

hope this helps

it sounds like the driver seat module. It controls all of these items.
buy used at car-part.com. look on page with * for lowest price.
buy new at discount at tascafordparts.com

• The memory mirror is inoperative

• Driver seat module (DSM).
• Circuitry.
• CJB fuse 3 (7.5A).
• Exterior mirror motor.
• Mirror control switch.

• The memory seat is inoperative

• Circuitry.
• Seat control switch.
• Seat track.
• DSM.
• PDJB Fuse 109 (30A).
• Power seat motor.

• Adjustable brake pedal does not operate correctly — does not operate using the adjustable pedal switch

• Battery junction box (BJB) fuses:
  • 109 (30A).
• Circuitry.
• Switch.
• Adjustable pedal motor.
• Driver Seat Module (DSM

Check with VOM (volt ohm meter) 3 to 5 bucks at harbor freight.
...with current connected check voltage at each pole of switch while pushing in the respective direction.
...Can also try electrical contact cleaner spray into switch as a potential quicky test/solution---often the contacts get arc residue/resistance.
..if replaced the mirrors then you know where the wiring harness connector is, and can check the voltages on each pin while moving the switch--thereby seeing which pin is generating something and which is pole/switch position is doing nothing (if connector is more accessible than switch blade connectors.

pull the power mirrir switch and test it with a 12 volt test light, these test lights are very cheap (approx $6) and pay for themselves the 1st time u use them.

but still no fire to the mirror switch ????? B+ voltage ! CTSY fuse # 3 - 20 amp , location insturment panel fuse block . You check this one ?