77 C30 Power window & Lock wiring issues

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Juggernaut

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Greg
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78
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K20
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350
Yes, you can use the 30 amp relays. I did this on my truck. The original switches were slow and had to be activated two or three times to fully lock or unlock. Relays corrected that problem. Used 82 and up switches with my original actuators and harness. I purchased a 5 pack of relays off Amazon, I think it was about $30. Used 2 relays on each side. Right 2 relays are the windows, left 2 are locks
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91frppgt

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randy
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Could you provide how you wired the relays to the locks?

Thank you!
 

91frppgt

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randy
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Yes, you can use the 30 amp relays. I did this on my truck. The original switches were slow and had to be activated two or three times to fully lock or unlock. Relays corrected that problem. Used 82 and up switches with my original actuators and harness. I purchased a 5 pack of relays off Amazon, I think it was about $30. Used 2 relays on each side. Right 2 relays are the windows, left 2 are locks
You must be registered for see images attach

Could you provide how you wired the relays to the locks?

Thank you!
 

91frppgt

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Joined
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Location
houston
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randy
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77
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c30
Engine Size
l86
i'm trying to test the tan/gray wires going to the locks, but I can't get the lock to function. putting one to ground and the other to battery and swapping, but nothing is happening with the lock actuator. could it be the actuator is bad?

i was planning on using a bosch 4 pin relay.

pin 30 to 12v battery
pin 85 to ground
pin 86 to 12v acc.
pin 87 to power on switch

I tested this method and not working.
 

Juggernaut

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Location
Illinois
First Name
Greg
Truck Year
78
Truck Model
K20
Engine Size
350
Could you provide how you wired the relays to the locks?

Thank you!
You should have a diagram on your relay that looks like the picture below. On this relay 85 and 86 are the coil. You want to put one direction of the switch on 85 and 86 to ground. 30 is called common, it needs to go to one of the wires on the lock solenoid. 87a is normally closed, it goes to ground. 87 is normally open, and it goes to your new power source. Make sure you use a fuse on your power wire. Use a second relay for the other direction. If it runs backwards, swap the two wires on 30
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