How do you test 2009 Tahoe front wiper motor/wiring

[Blk 09 LTZ]

My front wipers suddenly got extremely slow, and actually stop until I push then manually a bit. I checked the fuse under the hood and it appears okay. I can start the wipers by turning the switch down for a single sweep, but it stops after an inch. Same thing on all the other speeds if I turn the switch up. I found two wiper TP spots on the fuse block, but don’t know how to use them with my multi tester. And I don’t know what color wires on the motor connector are used for 12v, ground, or speed resistances, if I find the motor connector under the cowling at the base of the windshield. I tried the battery disconnect to see if a reset would work to no avail. Does anyone know how to use the fuse block TP’s? And does anyone know what the wire colors represent? And finally, does anyone have any other suggestions for trouble shooting?
Thanks, Bob

 

[wjburken]

My front wipers suddenly got extremely slow, and actually stop until I push then manually a bit. I checked the fuse under the hood and it appears okay. I can start the wipers by turning the switch down for a single sweep, but it stops after an inch. Same thing on all the other speeds if I turn the switch up. I found two wiper TP spots on the fuse block, but don’t know how to use them with my multi tester. And I don’t know what color wires on the motor connector are used for 12v, ground, or speed resistances, if I find the motor connector under the cowling at the base of the windshield. I tried the battery disconnect to see if a reset would work to no avail. Does anyone know how to use the fuse block TP’s? And does anyone know what the wire colors represent? And finally, does anyone have any other suggestions for trouble shooting?
Thanks, Bob

Here is a link to the schematic for your vehicle (2008 is pretty much same as 2009).
http://www.gmupfitter.com/files/media/photo/68/2008_LD_ElectricalPickupsChassisCabs.pdf
Look at page D-468. It gives colors for wires going to the motor.

 

[Blk 09 LTZ]

Thanks for the diagrams, they were helpful in checking the wiper motor wiring. Thing is, when I finally got the motor out(have to take the whole wiper linkage out), I found the motor is fine but the linkage is seized! So off to the parts shop to get the Dorman linkage. It appears the Dorman unit has clips to hold the wiper shafts in place, so if it slows down at least I can take it apart and lube it unlike the OEM.

 

[wjburken]

Thanks for the diagrams, they were helpful in checking the wiper motor wiring. Thing is, when I finally got the motor out(have to take the whole wiper linkage out), I found the motor is fine but the linkage is seized! So off to the parts shop to get the Dorman linkage. It appears the Dorman unit has clips to hold the wiper shafts in place, so if it slows down at least I can take it apart and lube it unlike the OEM.

Glad to hear you found the issue and thank you for sharing the resolution here for others that may experience the same issue. Many times folks come here with a problem and get some suggestions for solving their problem but never respond with the resolution.