BretD04GMC

Considering the new GM full-size trucks (with options) will probably be in the high $40k to $50k+ range, this sounds like a bargain.

Minimal increase in MPG. Nothing significant. It's essentially a regular full size truck with an autostart/stop function and the generator ability. I wasn't expecting any huge MPG gains when I bought the truck. What appealed to me was the generator capability. Also, it was well equipped with only 6,000k on it. Initially it was a GM fleet vehicle and my local dealership bought it at auction after GM was done with it. So, it was basically an "almost new" truck and I got it for around $10k less than what it would have cost were it brand new. All in all, it's been a really reliable truck and I've been really happy with it.

Did some reading in the manual tonight. The hybrid batteries are Panasonic HV1255 Valve Regulated Lead Acid. Reading the test procedures for the P0A7F code, it says that if the batteries test good, then proceed to Testing for Intermittent Conditions and Poor Connections. I don't know that the tech did that. The paperwork from the dealership just says – "possible battery pack". Some online searching came across this: http://www.justanswer.com/chevy/4kzr5-chevrolet-silverado-1500-classic-hybrid-2005-chevy.html Sounds like this is a dealer only repair.

I've got the full set of GM service manuals and the hybrid system is covered. I haven't gone thru all of the battery info. but from what I have read so far, it doesn't sound complicated. Basically, disconnect the batteries using the disconnect switch, remove and replace, turn the switch back to the connect position. It does say though, that the hybrid batteries are not at full charge when shipped and need to be completely charged before installing them. I'm not sure if there's a special charger required for this.

Yes, GM introduced the hybrid trucks in the 2004 to 2007 GMT 800 model run – although, technically, they weren't true hybrids. There's no electric drive to the wheels. Just engine auto-stop to eliminate sitting at idle when stopped, and the onboard generator feature with 120v GFI outlets in the cab and bed. Rather than a traditional starter motor for the engine, instead there's an electric motor coupled between the engine and transmission. This electric motor does a couple things: 1) Starts the engine, getting it's power from the hybrid battery pack. 2) Recoups energy while braking to charge the hybrid battery pack. So, if the hybrid battery pack fails, there's no juice for the electric motor to turn the engine over. There is also a conventional battery under the hood, but this runs the lights and accessories. If that battery goes bad, the truck still won't start, but at least you can usually jump start it. Switching on the defroster or turning on tow/haul mode will disable the auto-stop function, so the truck is at least driveable.

I've got a 2004 GMC Sierra 1500 Hybrid. I'm getting an intermittent diagnostic code of P0A7F (Hybrid Battery Pack Life). Took it to my local dealer to have them check the system out. Test of the hybrid batteries shows they are currently OK, but the tech advised they are probably reaching the end of their life span. Dealer's recommendation was to continue driving the truck and keep an eye on it. Should they need to replace the hybrid batteries (3 total), repair estimate would be $1,405.00. They stated there's a 2 hour diagnostic procedure that GM requires before replacement batteries can even be ordered. I've found online GM parts suppliers that list the batteries at an MSRP of $206 each, but offering online pricing as low as $150 each. One inquiry I submitted to confirm the pricing came back with a response of "We can't supply these batteries". I'm wondering if it's possible for a DIY consumer to purchase the batteries and replace them myself – for much less than $1400? Or does GM have a lockdown on them? My concern with continuing to drive the truck right now is that – IF one or more of the hyrbid batteries does indeed die – I WILL be stranded somewhere with a truck that won't run. Shortly after buying my truck back in 2005, one hybrid battery did go bad and the truck wouldn't start. GM replaced that battery for FREE, but I am now outside of the 8 yr./100,000 mile hybrid component warranty. Thanks!