neat find under my cab carpet/insulation in the '78
 

I was stripping the interior of my '78 GMC today, and when I pulled up the insulation, I found this '77? wiper switch. I think that my '78 was one of the first ones off the assembly line, and I'm wondering if it had the wrong wiper switch installed? It also has cruise, maybe that's it? Either way, I've got an NOS wiper switch on the shelf.

Re: neat find under my cab carpet/insulation in the '78
 

comparison to one in dash

Re: neat find under my cab carpet/insulation in the '78
 

Working on the assembly line myself, there were always loose parts and tools dropped in the vehicle during assembly. Now if no one would get the loose items before the carpet was laid, then they were there for good.

Re: neat find under my cab carpet/insulation in the '78
 

Looks like a regular switch and your switch is for delay wipers

Re: neat find under my cab carpet/insulation in the '78
 

delay wipers, gotcha....cool

Re: neat find under my cab carpet/insulation in the '78
 

I found a Dixie cup with Oshawa factory lettering under my carpet, I thought it was neat find.

Re: neat find under my cab carpet/insulation in the '78
 

Nos!

Re: neat find under my cab carpet/insulation in the '78
 

What led you to believe your '78 was on of the first ones off the line? Can you post the VIN? (You can X out the last couple digits).

Thanks

K

Re: neat find under my cab carpet/insulation in the '78
 

I found a NOS bolt under my carpet. What factory was your truck built in?

Re: neat find under my cab carpet/insulation in the '78
 

My dad had that same model brake control in his Scout II back in the seventies, cool stuff!

Re: neat find under my cab carpet/insulation in the '78
 

yeah, I'm going to remove the brake controller, compass and altimeter, but I may leave the cb..

Re: neat find under my cab carpet/insulation in the '78
 

Vin

Re: neat find under my cab carpet/insulation in the '78
 

Old CBs FTW! Let's see it.

Re: neat find under my cab carpet/insulation in the '78
 

Just an FYI - that’s a hydraulic brake controller. Removal is a bit more complicated than disconnecting wires.

Re: neat find under my cab carpet/insulation in the '78
 

The sequential portion of the VIN is the last six digits, so I'd like to see one more digit, but even if it is a "one" that would make it 140018.

VINs for Chevrolet trucks in 1978 started at 100001, which would make this around 40,000 Chevrolet units in. Additionally, GMCs often had their own VIN sequence, starting at 500001 (for example) and would be interspersed about one every nine or so vehicles inbetween the Chevys, on the same assembly line, pushing the build back further.

Just a couple other considerations for conversation purposes:

a) VINs do not indicate build sequence. The General Assembly sequence number is what tracks that value, but is not recorded and therefore typically lost to history. The VIN numerical portion is assigned sequentially, but within other constraints like nameplate based on the receipt of the order number at the specific plant. It's not too bad if it is just Chevrolet and GMC, but if a plant is building Buick, Olds, Pontiac, Chevrolet and Cadillac all down the same line you can see how the VIN would diverge quite rapidly from an actual build sequence indication.

b) There is no correlation between VINs at the various assembly plants. Each plant increments up based on its own production cadence (basic line rate, overtime, extra production days, holidays, downtime due to material shortage or other disruptions) with no relationship to any other plant. There were about seven final assembly locations building squares at this time, with Flint Assembly typically being the "lead" plant when it came to new product launch (due to its proximity to Chevrolet Engineering and Chevrolet "Headquarters").

I would guess your truck was built about 45,000 or so units into the 1978 model year for that specific assembly plant (which you did not name).

Probably a bit late in the model year to attribute it to any kind of "new model" blues. Those are usually ironed out within the first few days of production start up.

My guess is the operator grabbed the wrong part for the truck and when he/she realized the mistake just pitched (or dropped) the part on the floor, and then installed the correct part, especially since the part you found would be the "base" (or the "default") part and would be the part to be installed 9 times out of 10; the pulse wipe switch would be optional content. Pulse wipe was available in both '78 and '78 so it's not like it was new content.

Pulse Wipe is RPO CD4 ("Windshield Wiper System - Intermittent"):
https://www.gmheritagecenter.com/doc...olet-Truck.pdf

K

Re: neat find under my cab carpet/insulation in the '78
 

lol, I think I'm going to need more VIN info than that/
yeah, there's a couple of hard lines to remove on that brake controller

Re: neat find under my cab carpet/insulation in the '78
 

Sorry.

Summary:

a) Not one of the first off the line

b) Not a '77 part

K

Re: neat find under my cab carpet/insulation in the '78
 

Is the pulse wiper unit a plug and play upgrade for a non pulse wiper unit?

Re: neat find under my cab carpet/insulation in the '78
 

hahaha...KS, lighten up...you missed the sarcasm tag on my post...it was in reference to the length of that post you made...got it, you're the guru of all things chevy truck

Re: neat find under my cab carpet/insulation in the '78
 

There's a separate module required in addition to the switch.

My 80 was built with the base wiper system but somehow ended up with a pulse wiper setup before it was all over.

K

Re: neat find under my cab carpet/insulation in the '78
 

Roger - I'm never quite sure how much to say.

Somewhere between those two responses apparently.

Believe it or not there's a guy on the Pontiac board that's worse than me.

K

Re: neat find under my cab carpet/insulation in the '78
 

I appreciate the info...you're right on that Vin; there's a 4 there...good to know

Re: neat find under my cab carpet/insulation in the '78
 

I really enjoy seeing this kind of information. Lets me picture what might have gone on with one of my rigs. Don't ever hesitate Keith, OP can skip over it if they aren't interested. We all learn from this information.

Re: neat find under my cab carpet/insulation in the '78
 

I agree, I enjoy reading what Keith posts about Build sheets, Vin numbers and sequencing. I understand a lot of what is said about it, coming from working on an assembly line myself. He just explains it a lot better than I ever could. :lol:

Re: neat find under my cab carpet/insulation in the '78
 

Just gotta say you guys know your stuff wow! I would also like to know if this pulse system could be integrated into a standard setup as I need to replace my wiper switch.