Help, Dtc39 & Dtc68

[chris_maxwell]

bought a small trailer and coming back for SC i had what seemed to be little power, lots of smoke and checking when i got home had codes 16,39,68. where do i start?
1995 GMC with 117K miles

[john8662]

First step,

visit:

http://www.thedieselpage.com/members/trblcode.htm

From the looks of things, all the codes mentioned are all tranny related. So you'll want to figure out what's going on there. Could be bad electrical connections. Check the connection on the side of the transmission, as well as the ground straps on the engine, that help ground the harness.

For the black smoke, it could be that you're not getting an turbo boost. This is usually a fault the vacuum controlled boost system. This consists of three main components, the vacuum pump, the vacuum tubing to and from the vacuum pump, wastegate solenoid and the wastegate actuator on the turbocharger.

Do some searching on the forum for "no boost" or "black smoke" and you'll find tons of information on those symptoms.

J