SuthernFlames316

I have a 99 GMC Z71 ex cab. Everytime I shift in drive/reverseand press the throttle, there is a "thump/bumb/clunk" noise, just one, coming from under the floorboard. As soon as the noise happens, my volt meter drops instantly. This process happens in the blink of an eye. It is right under my feet where the shift cable runs.
The noise will not occur if I do not press the throttle. I can shift in gear and move by idling and it will not happen.
I went to check the alternator and battery. Everything is perfect. The mechanic said "it could be a solenoid"

This problem is pissing me off. Any suggestions????

SuthernFlames316

anyone?

NoChrome

iTrader: (1)

Does your drive shaft have any play in it, (can you turn it while parked, e-brake off)

stone150

iTrader: (2)

sounds like the slip yoke to me, be can't explain the voltage drop other than the tranny shiffting form park

NoChrome

iTrader: (1)

Thats what I was thinking... kinda weird.

Hey Josh got the decal on, Bad ***. Your the man!

SuthernFlames316

no play in driveline. the voltage surge does not occur when shifting out of park. it happens only once during the initial takeoff when i press the throttle for the first time after shifting out of park. the clunk happens and the meter drops down to like 9 volts instantly and then goes back to normal 14. it happens in an instant.

shandy294

Do you have the repair manuals? Maybe a elec. component in the trans or a rubbing wire near the trans?

negativeswitches

iTrader: (15)

how long do you wait from switiching from r to d cause if the trans doesnt not build up pressure again to apply the correct gear it will surge line pressure when reving hesitate cause of the clutch slippage and then go also going to jolt the drivetrain prolly causeing a clunk