Please help with Trans Error codes!

dawsonX · 05-07-2008, 04:27 PM

I just picked up my first duramax and on the drive home I felt a miss and the service engine soon light came on. Checked the codes:
1. P0380 glow plug error
2. P0700 Transmission Control Malfunction
3. P0734 4th Gear incorrect ration

Can anyone tell me what these all mean and possible fixes to them. thanks

**BigRedChevy** · 05-07-2008, 04:30 PM

Did it go into limp mode, locked in 3rd gear?
What kind of driving conditions caused it to happen?
Did you check the tranny fluid level?
Do you know the last time the fluid and spin on filter was changed?
Does it have a programmer on it?

dawsonX · 05-07-2008, 05:41 PM

I was excellerating from about 30 to 55, not real hard but not easy with the truck empty no trailer. I believe it went into limp mode, felt like it was slipping, but I'm not sure what the limp feels like. I checked the fluid and its good, looks clean but I am not sure when the last time it was done, being I just purchased it. I don't think it has a programmer, nothing visible in truck or under hood, Dealer did not say anything about progammer.

**daddysLBZ** · 05-07-2008, 06:57 PM

Check spin on filter,I always change mine every 10,000-15,000miles,need it or not.Fluid always bright red,looking good...

**BigRedChevy** · 05-07-2008, 09:02 PM

I would start with a fluid change and spin on filter and go from there. 4th gear is not the normal one to slip if the tranny was going out. Usually 5th is the one that will slip on you so maybe it's something simple.

dawsonX · 05-07-2008, 09:28 PM

Ok I will start with that and go from there. Thanks for the info.
Any thoughts on the glow plug code. Truck did it again after I cleared it tonight.....

**BigRedChevy** · 05-07-2008, 09:35 PM

Could be the glow plug module. Some of the trucks had a problem with it. also check all of the connections.

tommy469 · 05-07-2008, 09:35 PM

make sure that the NSBU switch is pluged all the way in

dawsonX · 05-07-2008, 09:42 PM

I will check the glow plug conections. Where exactly is the NSBU switch to check that??

**BigRedChevy** · 05-07-2008, 09:43 PM

the NSBU swith is on the driverside of the transmission and was bad about going out on that model. I forgot about it to tell you. That could be your problem, but most of the time you gear indicator would flash when it goes out.