'78 K20 wiper and headlight switch selection help needed!

I'm pretty sure one of the previous owners of my truck installed the wrong gauge bezel from an earlier truck, because they modified both holes in the bezel for the wiper switch and the headlight switch. I can get a new bezel at some point, but I need to figure out if I have the correct switches before I do that. The truck has a tilt wheel and factory cruise control (not currently working, but I'd like to fix it later) and I does not currently have intermittent wipers. My questions: 1. What are the part numbers or switch types I should have, 2. How do I know if it came with intermittent wipers?, and 3. Why do my wipers not stop at the "parking" position when I turn them off? Thanks!

1973-1974 bezel


Switches look correct for a 78, if you had intermittent/delay wipers it would have a round knurled knob that rotates instead of that rectangle chromed wiper switch.

That picture is weird. It looks like you should have a numbered reference part, not a letter. How cruise would impact the choice is beyond me on a dash mounted wiper switch ...
Intermittent switches look like number 4 and have a black round know ( # 6) to control the delay. I would ASSUME that they bought the same style replacement ad what was already there or that those are the OE switches. I do not know how to ID what you need if they are not the OE ones nor can I answer the park question.

Sorry.

legopnuematic said:

1973-1974 bezel

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Switches look correct for a 78, if you had intermittent/delay wipers it would have a round knurled knob that rotates instead of that rectangle chromed wiper switch.

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Yep, the spare bezel that I have is definitely a 73-74, and I think the one in the truck (earlier photo) is too, as it looks like someone cut off the conical base around the headlight switch so it would work with the 78 style switch.

Goldie Driver said:

That picture is weird. It looks like you should have a numbered reference part, not a letter. How cruise would impact the choice is beyond me on a dash mounted wiper switch ...
Intermittent switches look like number 4 and have a black round know ( # 6) to control the delay. I would ASSUME that they bought the same style replacement ad what was already there or that those are the OE switches. I do not know how to ID what you need if they are not the OE ones nor can I answer the park question.

Sorry.

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I would tend to agree. It seems likely that someone would match the switch that was in it, so it probably didn't have intermittent wipers to begin with.

Thanks, guys, that's helpful. You have confirmed my suspicions that I have the right switches for the 78, wrong bezel. Now I just have to get a new bezel, figure out why the wipers won't park when I turn them off (probably a corroded connection), and get the washers working.

Goldie Driver said:

That picture is weird. It looks like you should have a numbered reference part, not a letter. How cruise would impact the choice is beyond me on a dash mounted wiper switch ...
Intermittent switches look like number 4 and have a black round know ( # 6) to control the delay. I would ASSUME that they bought the same style replacement ad what was already there or that those are the OE switches. I do not know how to ID what you need if they are not the OE ones nor can I answer the park question.

Sorry.

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Some of LMC(and others) parts listings are wacko. Like they list the turn signal switch for a 78 for "non tilt" only, when tilt and non tilt use the same switch.

BigT said:

Yep, the spare bezel that I have is definitely a 73-74, and I think the one in the truck (earlier photo) is too, as it looks like someone cut off the conical base around the headlight switch so it would work with the 78 style switch.


I would tend to agree. It seems likely that someone would match the switch that was in it, so it probably didn't have intermittent wipers to begin with.

Thanks, guys, that's helpful. You have confirmed my suspicions that I have the right switches for the 78, wrong bezel. Now I just have to get a new bezel, figure out why the wipers won't park when I turn them off (probably a corroded connection), and get the washers working.

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Probably the park switch in the motor is bad.

The wiper motor can be checked by removing the washer cover. The Park Switch is in the upper section just a tad left of center. Just clean the contacts.
Sorry. I have no pix.