GM Code P0802

[Kodiak]

Wondering if anyone has come across this. 2003 GMC 2500HD 8.1L with 4 speed auto Allison.
Out of the Blue won't crank. Lots of juice ( new Battery, 12.51 V, 800 amp hold ), replaced starter. Then cleared the code, all good until I shut it off. Same code. Picked up a new Neutral safety switch, that's my next step. All fuses and relays test out good.

Thanks in advance.

[Puma]

Did you google the code ?

Lots of stuff on it. ie The P0802 is an ECM code that sets when the transmission module requests that it turn on the check engine light.

[Sooner]

Google is your friend, i bought the scanner, google tells me what the code means and then I know what part I'm changing

[Gerry]

Just found this for you.

https://www.autocodes.com/p0802.html

https://www.autocodes.com/tsb/gmc/topkick/2003.html

[Kodiak]

Yes, googled it. There are so many different things that can cause it though. Mine didn't trigger the check engine and the selector indicator works perfectly. Just all of a sudden wouldn't crank. Of course mine has no common problems most have experienced. Frustrating !!

[Sooner]

I have a new code on my tired Explorer. Low idle which i noticed the last couple weeks before the code showed up. Probably at least 6 different possibilities as to the cause, each one getting progressively more expensive.

You can search some GM forums. I find the forums can help eliminate changing too many parts first as guys who have had the issue tend to know what to look for first. Hope it's not the ECM, expensive part.

[Kodiak]

Being old school, immediately brain said starter. 250 bucks later, soaked, muddy, frozen fingers and still DEAD !! So 100 bucks to go 6km for a tow to our plant, tested everything on the wiring diagram still DEAD. Scanned it again, nothing but this time I cleared about 3 times and start !! Drive home and dead again. Scan it again and whammo P0802. The only thing I didn't do was jump the NSS so I bought one.

[Kodiak]

Next will be the ignition switch. It's intermittent so what else can a guy do !!

[Puma]

Still sounds like the starter to me. Check the power to the starter when it wont start.

I just went through a similar issue with my 2004. Would start 10 times in a row, then nothing. Would go everytime with a boost. Changed out the battery, it was good for a week, then same thing. Then I thought it was the cable, I saw online they have been an issue with internal corrosion.

Turned out, it was a bad starter.

[jrowan]

[1899b]

Originally Posted by jrowan

Valuable info! Nice job...

[Kodiak]

Thanks Guys, I'll post how it turns out if it ever quits snowing / raining !! Hopefully soon, not used feeling like a bug on the road in a Malibu, not to mention the different way you get treated...............

[cole smith]

Check cables and connections are good. I've seen a lot of no starts that were it turned out something simple. If battery cables are good I'd check the plugs at the modules, I don't know about Chevy but some dodges I've owned have the modules wear out at the plug, if safe to do so have someone carefully/slowly wiggle the plugs while trying to crank. If a wiring diagram is available I'd also check any grounds in that circuit, grounds can do some funny things.

[Reeves1]

[Kodiak]

Very Funny Reeves, now I know why you operate the Hoe and not work around it........

Turned out to be the Neutral Safety Switch on the outside of the Allison. Just a FYI, make sure you have a heat gun for the top plug. Some nasty Glue type stuff, almost like a hot Glue gun stick. Heat to take off and to reinstall.

Big thanks to everyone for the info !! Frustrating to say the least.

[Reeves1]

Work around it & I'd get dirty boots !




However, I also do custom work ..... on small cars

[Reeves1]

[Kodiak]

Lol

[overhere]

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