Passenger window troubleshooting, help please

[tj43]

The 88 Suburban is being moody. Last week it was the heater core, this week it’s the passenger front window. That window has always had an intermittent issue. Specifically, it has always worked from the passenger side switch (even when the driver’s side is being moody), but it only works intermittently from the driver’s side.

Yesterday, after finishing the heater core swap, it went down perfectly fine from the driver’s side switch. But now, it wants to stay there. No movement from any input at either switch. All other windows function properly.

First question: could I have done something during the heater core swap to cause this?

Second question: how do I even start diagnosing this? I am a complete neophyte when it comes to the electronics in older cars—so speak to me like I am really dumb (because, in this instance, I am).

I have this tool (photo below). I have no clue how to use it. Thanks in advance and I apologize for being so daft on this one.

 

[RustyPile]

Check your "conversations", I sent you a message..

 

[tj43]

Nick. Thanks for the message. I just responded.

 

[squaredeal91]

Likely it's the master switch or switch connections. I have problems with mine. Sometimes I have to wiggle the switch

 

[Scott91370]

I had this issue on mine (only 2 door truck) and the connector/plug on the switch had a broken wire. Sometimes it was close enough to work other times nothing. Super easy fix but my diagnosis was just pulling on the wires.