wiper question

[Big GMC truck]

My wipers will only work on the high speed setting. Is this a wiper motor problem or a switch/ electrical/wiring problem. By the way, the truck is 22 years old. How do I troubleshoot this? Any help is appreciated.

 

[AV8]

I changed the wiper relay in my truck and fixed that problem.

 

[Big GMC truck]

Where is the wiper relay located on a 1984 K1500?

 

[1985_K5_Silverado]

My '85 K5 GM shop manual troubleshooting chart says that if the wipers work, but have "Hi" speed only, it is likely to be:

An open circuit in wire (#3 terminal on wiper motor) to wiper switch. Fix: locate and repair broken wire.