'99 7.4L, what is this sensor?

[454cid]

I'm not sure of the assembly date, I don't have a door sticker. Do you know of anywhere else it might be? I'm still learning about these things, but this was based on the old guy at the auto parts store who generally knows his stuff (a real auto parts store, not Autozone/Advance). He said the door handle style indicates if was after May of '99 or not. I know there was some renaming of models and other BS right around that time, and there doesn't seem to be a 7.4L after '99 (went to a 8.1L I think?). If I've got that wrong, please edumicate me

This is a C3500 HD, and it's got a dump chip box on it (the type tree removal blow chips into from the tree shredders). I haven't crawled on top of the engine to try to get a really good look back there. I'd like to find the block stamping, which I'd assume is on the back somewhere. There's no sticker on the valve cover, unfortunately.

I don't have time for a good reply right now since I'm on my way to work. Your Auto Parts guy is in the weeds. At this point your idea of disconnecting the wiring and checking out the dash gauge is probably your best bet.

 

[454cid]

I'm not sure of the assembly date, I don't have a door sticker. Do you know of anywhere else it might be?

I found out my build date when I ran my VIN through compnine, back when it was free.

I'm still learning about these things, but this was based on the old guy at the auto parts store who generally knows his stuff (a real auto parts store, not Autozone/Advance). He said the door handle style indicates if was after May of '99 or not.

Door handles sounds like he's thinking GMT-400 vs GMT-800. We already know your truck is a GMT-400. That's why I said he's in the weeds. I'm not sure why May of 99 would be significant..... I do think that's the month GM/AAM switched to synthetic gear oil in rear axles, but that's not applicable to this situation.

I know there was some renaming of models and other BS right around that time, and there doesn't seem to be a 7.4L after '99 (went to a 8.1L I think?). If I've got that wrong, please edumicate me

GM redesigned the 1500 and light duty 2500's for the 99 model year, basing them on the GMT-800 platform. There were still GMT-400's being made, very few were 1500's, and quite a number of 3/4s and ALL 1-tons. The new GMT-800 HD trucks weren't a thing until the 2001 model year. 99 was also the year GM changed "Silverado" from a trim level to a model name. Here's the thing.... this has very little to do with your 3500HD, other than name confusion. Your truck is not a regular 1-ton. It's not a beefed up 1-ton.... bigger springs, better brakes, whatever. Your truck uses a completely different chassis, and is closer to a medium duty. The new GMT-800 Silverado 3500HD is NOT the new version of you truck. It's a regular 1-ton pickup truck. Your truck was made thru 2002 for the US market. The closest thing to your truck after that would be the then new 4500.

This is a C3500 HD, and it's got a dump chip box on it (the type tree removal blow chips into from the tree shredders). I haven't crawled on top of the engine to try to get a really good look back there. I'd like to find the block stamping, which I'd assume is on the back somewhere. There's no sticker on the valve cover, unfortunately.

Good look back there? LOL, you pretty much have to feel for it. Someotherguy has a good picture of it out of the truck. He put a Vortec 454 out of a wrecked pickup into an HD.

 

[jcwren]

Lots of good stuff there, thanks! I wonder if I can use a endoscope camera to get a look at the block stamping. It's probably crudded over, but it's worth a try.

Here's the RPO sheet from the truck. The VXT option probably explains why the VIN decoders will only do a partial decode on it.

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[someotherguy]

"Incomplete vehicle" just means it's a cab and chassis model. This can also be decoded from 3rd digit of your VIN. Truck is sold essentially complete other than the bed, goes to an upfitter for whatever purpose. Box truck, dump bed, wrecker unit, etc. and the builder has to affix a sticker to the door jamb indicating who built it and when, axle weights, tire pressures, etc. in accordance with the equipment they've added.

In fact I can just about guess more than half of your VIN 1GDKC34J_XJ_______
Just gonna be missing the check digit and the 7 digit unique serial #.

Richard

 

[jcwren]

In fact I can just about guess more than half of your VIN 1GDKC34J_XJ_______
Just gonna be missing the check digit and the 7 digit unique serial #.

Richard

Very close. XF, not XJ

Curiously, there is no door jamb sticker. And I don't see any faded paint, sticker residue, etc to indicate where one might have been. It has the federal compliance disclaimer sticker, but that's it. It had a USDOT number at one time, and I'm would have thought the would have needed to check the sticker.

 

[someotherguy]

Very close. XF, not XJ

Curiously, there is no door jamb sticker. And I don't see any faded paint, sticker residue, etc to indicate where one might have been. It has the federal compliance disclaimer sticker, but that's it. It had a USDOT number at one time, and I'm would have thought the would have needed to check the sticker.

Really.. 11th digit F instead of J? Truck was built in Flint MI, not Janesville WI? Weird for an HD. Anyhow, pretty close

Those stickers didn't always hang on too well over the years especially considering these were pretty much all work trucks. If it got repainted at any point, that's another factor. If the door ever got replaced you'd be missing the VIN-specific one, or have a mismatched one. The upfitter's sticker would generally be on the jamb but not guaranteed.

Richard

 

[jcwren]

Turns out this is technically a GMT-455 truck, and according to this link, "The Flint 3500hd line started in 1997. Only Summit White cabs sold for domestic use were produced here. All other 3500hd units were still produced at the Janesville plant."

I guess since the paint code on the RPO sheet is Summit White, that explains why it's a Flint truck.

Trying to find any service manuals, up-fitters guides, or any other documentation that pertains to the GMT-455 chassis. Little luck so far, but the search has only just begun.

 

[someotherguy]

Turns out this is technically a GMT-455 truck, and according to this link, "The Flint 3500hd line started in 1997. Only Summit White cabs sold for domestic use were produced here. All other 3500hd units were still produced at the Janesville plant."

I guess since the paint code on the RPO sheet is Summit White, that explains why it's a Flint truck.

Trying to find any service manuals, up-fitters guides, or any other documentation that pertains to the GMT-455 chassis. Little luck so far, but the search has only just begun.

Technically yes, each variation of the GMT400 line has its own designation.

The factory service manuals for the C/K trucks include 3500HD-specific info. You can find 'em online here, or pay some decent coin for paper versions. I prefer paper as it's easier for me to look at and find things, but the downloads sure are handy (and can't beat the price.)

Richard

 

[jcwren]

Well, what's odd (actually, more annoying than anything) is that the truck doesn't match the '99 FSM for some things. Here's an example: The '99 FSM shows this wiring diagram for the fuel balance module. The 2nd wiring diagram actually matches what's on the truck, but it's ONLY that one image, and it came from some "justanswer(dot)com" post, with no attribution or anything. I'd like to find the original series of documents the second post came from. Third picture shows what's on the truck (matching the second wiring diagram).

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[someotherguy]

Things get weird for the last few years of the generation. Is the '99 manual you're looking at for C/K trucks (GMT400) or Silverado (GMT800) ? Both extant at the time and the source of much confusion when buying parts or looking up service info. What compounds the confusion are last-minute design changes that may not have filtered down into the available information.

Richard