SD51
Silver Member
- #1
Thread Owner
I know this is a "car related" question on T-Net, but I'm getting no help on car forums and there's a great group of people on this site that might be able to help!
Here's the question...
My neighbor called and asked if I could help figure out why the blower motor on his 2006 Buick Lacrosse stopped working. He had already bought a new blower motor, a new blower motor resistor module and purchased an HVAC module from a used parts supplier. When all the new parts were installed, the blower still wouldn’t operate.
I pulled up the schematic for the blower motor circuit for the 2006 Buick Lacrosse, and it shows the +12 volt supply from the battery to the resistor module uses a 30 amp fuse, and passes through two connectors (C4 and C210) before connecting to Pin C of the resistor module. The fuse wasn’t blown, but there isn’t 12 volts at Pin C with respect to ground.
We located connector C210 which supplies the +12 volts and the ground connection to the resistor module and confirmed there wasn’t 12 volts at the connector either. We suspected a problem at Connector C4, but couldn’t locate it.
To confirm our finding, I ran a separate +12 volt wire from the battery through an in-line 30 Amp fuse and connected this wire to Connector C210. We also ran a separate ground wire to C210 from the battery. The blower motor worked perfectly as we cycled through all the fan speeds.
I disconnected the new ground wire to C210 and attached the original ground wire and the blower still operated, confirming the problem is with the +12 volt wire between the fuse and Connector C4. I suspect the contacts are possibly corroded in C4, but we cannot locate Connector C4.
Do any of you Buick car guys know where Connector C4 is on the wiring harness? I know we could purchase the Chilton manual but I don’t know if it will show that detail.
Sure would appreciate any help!!!

Here's the question...
My neighbor called and asked if I could help figure out why the blower motor on his 2006 Buick Lacrosse stopped working. He had already bought a new blower motor, a new blower motor resistor module and purchased an HVAC module from a used parts supplier. When all the new parts were installed, the blower still wouldn’t operate.
I pulled up the schematic for the blower motor circuit for the 2006 Buick Lacrosse, and it shows the +12 volt supply from the battery to the resistor module uses a 30 amp fuse, and passes through two connectors (C4 and C210) before connecting to Pin C of the resistor module. The fuse wasn’t blown, but there isn’t 12 volts at Pin C with respect to ground.
We located connector C210 which supplies the +12 volts and the ground connection to the resistor module and confirmed there wasn’t 12 volts at the connector either. We suspected a problem at Connector C4, but couldn’t locate it.
To confirm our finding, I ran a separate +12 volt wire from the battery through an in-line 30 Amp fuse and connected this wire to Connector C210. We also ran a separate ground wire to C210 from the battery. The blower motor worked perfectly as we cycled through all the fan speeds.
I disconnected the new ground wire to C210 and attached the original ground wire and the blower still operated, confirming the problem is with the +12 volt wire between the fuse and Connector C4. I suspect the contacts are possibly corroded in C4, but we cannot locate Connector C4.
Do any of you Buick car guys know where Connector C4 is on the wiring harness? I know we could purchase the Chilton manual but I don’t know if it will show that detail.
Sure would appreciate any help!!!
