Mr. Z71

Try these numbers: 23164020 - Grey 23164021 - Black 23164022 - Dune Here's a link for a black one on eBay for a visual look at the part... https://www.ebay.com/itm/324869090918?hash=item4ba3b4ee66:g:8H0AAOSwARNiBCf3

Jordan... just for the heck of it run a temporary ground wire from battery negative to the truck body and see if there is any difference. I've seen this type of problem on older vehicles where the factory grounds looked good but were no longer doing the job. Won't cost you anything to try.

Not saying this is your problem, but you can replace just the sensor, you don’t have to replace the whole pump. If you have cut an access hole, it ought to be a breeze to replace the sensor. GM part number is 16238399. This is the one my truck uses, should be the same for yours. My truck is a 2003 GMC Sierra w/5.3L gas (not Flex Fuel) engine. Here’s a GM one on eBay … https://www.ebay.com/itm/353759723733?hash=item525db900d5:g:HpwAAOSwLgFch6tr

If it worked on your '99, then it should work on your '06 as OBDII became a standard requirement from '96 on up. You may not have all the bells and whistles as you would possibly have with a newer one, but you should still be able to pull codes. Sounds more like you have a power/ground issue to the scan tool.

Here’s my experience with a P0455 on my ’03 Sierra. Fought it on and off for a couple of years with a local non-GM repair shop (am unable to do my own repair work anymore) and over the course of those couple of years they replaced the vent valve and solenoid, relocated the filter, replaced the purge valve and I had replaced the fuel cap. Each time it was fine for a while but the DTC would return eventually. I finally took it to a GM dealership and they said it had a bad tank pressure sensor and replaced it. This cured the problem… been fine for almost a year now. After this, I looked back through my service records and found that the P0455 started setting after a fuel pump replacement. A non-GM pump with sensor was installed. This fuel pump went out a little under a year later and was replaced under warranty, again, with a non-GM pump and sensor. Once diagnosed by the GM dealership and replaced with a GM sensor the problem was fixed. I attribute the DTC to the fact that each fuel pump that was installed had a sensor that did not meet GM specs and thus, due to being out of spec, would throw the code eventually. Are you using GM parts? This is not the first time I’ve been bitten by using non-GM parts, happened with non-GM knock sensors on the same vehicle. Kept throwing sensor faults until the shop got tired of replacing them under warranty and finally put in GM parts. Voila… issue resolved.

Maybe time to do an EVAP Smoke Test to check for leaks?

You might message the eBay seller in the following link as he specializes in those model year trucks. He could probably answer your question. https://www.ebay.com/usr/daddydan717/

For what it's worth, at one time the 41-110 was listed for the older applications but changed to the 41-962 based on cost to keep ACDelco competitive. Either plug will work. See here... https://images.oreillyauto.com/parts/img/documents/acd/41-110.pdf

Thanks for clarifying this, I learned something. So if the relay fails you have to replace the fuse/junction block, correct? Who signed off on a design such as this?

According to Ace's website they can make them. See here... https://www.acehardware.com/automotivekeys

Someone correct me if I’m wrong, but I assume that due to the current draw of a horn, or horns (dual setup), a relay is required. I could find nothing in the owner’s manual referencing a horn relay or location of one, but shouldn’t the possibility of the relay contacts being stuck (welded together) be considered. Sure is what it sounds like to me. Again, I’m assuming that even the newer vehicles require a relay due to current requirements just as older ones do.

Pat... Here's a link to a TSB on what your problem could be and how it is resolved... https://static.nhtsa.gov/odi/tsbs/2012/SB-10038760-3962.pdf This TSB will give you a little insight on the history of this issue, however, warranty info will not apply due to age. Also, you can find these connector/pigtails and resistor modules on eBay. Do an eBay search for 15862656.

Possibly called a "cab floor support"? That's the only thing I could find referencing such a thing on other vehicles when I was searching.

If you really want accurate information that pertains to your specific vehicle and not the "one size fits all" type of manual, go with the factory Helm published manual sets. There are some decent used sets on eBay. Believe me they are the only way to go as far as I'm concerned. I've always purchased them new from Helm Inc. when I get a new vehicle, never been sorry for paying the price. Remember... you get what you pay for.

Hey Erob, here's a link for a TSB on the Castech heads showing how to identify them and where they crack... http://ww2.justanswer.com/uploads/Bluegorilla/2008-12-05_142924_Coolant_loss_5.3.pdf