no gas(diesel) pedal in reverse?

[Subzilla]

Daughter just got home from driving the '93. Said when she was backing up 2 different times, the rpm's went to idle no matter how hard she pressed on the gas pedal. It did not do the same when she shifted to drive and it drove perfect the rest of the time. Does this make sense to anyone?

[rapidoxidationman]

Just a shot in the dark:
Was she possibly touching the brake pedal as she was pushing the accelerator? Seems like on my '01 VW Tdi there was an override on the fly-by-wire throttle that would come into play under these conditions. Don't know about the venerable 6.5 (the '96 6.5 I had was a 5 speed and was the best truck I've ever owned...)

[john8662]

Surely you mean 94 right?

Recently I had something similar happen to me with my 1994 G20 van that has a 6.5 NA in it that's electronic with the DS4, coupled with a 4L60E Transmission.

The speedometer quit working on my 2nd day of ownership. The needle would just sit on zero. Well, when trying to figure out the issue I wiggled the wires on the speed sensor on the tail of the transmission. No change, but then I got a flicker on the speedometer, it bounced around.

Then all of a sudden I had no petal, I could floor it and all i got was Idle. So, I put the transmission into park, then back down again to drive and I had petal again when moving. Weird.

The problem ended up being a failed VSSB, cold solders could be seen on one of the chips on the board. I will probably attempt to fix it later. In the mean time I put on a spare one I had modified that could accept any ratio I wanted, so I matched the one that was in the van.

The speedomer works like it should now, and the issue with the throttle petal hasn't returned.

So...

That being said, does your speedometer act funny?

Check your codes and see what you have present. I had an APP code but I've cleared it since then and it hasn't come back. I'm thinking that it was related to the VSSB going wacky. Really really weird.

J

[greatwhite]

Step 1: 1993 or 1994?

Both mean very different problems.

Step 2: pull obd codes.

:)

[Subzilla]

Sorry, it is a '94. Got too many vehicles in the fleet - mixing up the years.

John, it did the same thing you described: no pedal in reverse, but then she shifted to drive and the pedal came back to life. She said it did this twice when she was backing out of our driveway.

Hasn't done it again since that one day. I drove it last night and it was perfect, speedometer and all. I will pull the codes and see what we have.

Sounds like an electrical gremlin in the works.

Where is the VSSB located? Another new area for my 6.2 self to learn!

Thanks for the thoughts.

[john8662]

VSSB it's in a little white box (4" x 4" x 1") behind the glove box liner next to the PCM. So, clean out the glove box, remove the liner screws, and it's secured by two tabs.

But.. I'd only mess with this if you're also getting the Vehicle Sensor Buffer Fault Code.

[Subzilla]

OK, it finally acted up with me driving but in a different way.

Fired it up at the store after sitting for 10 minutes. Ran for about 10 seconds then died. Restarted but got a lot of diesel clatter for about 10 seconds. Took off down the road and even though I had pedal, the power was about half to a third of normal power. Could not maintain 55 and the more I pressed on the pedal, the more it downshifted trying to get up to speed. After a couple of miles, I decided to stop the vehicle and shut it down. After 10 seconds of key off, I restarted and it ran perfect again and has for the last couple of weeks.


This happened to my wife a few months ago and I dismissed it as just a freak event.

Still haven't pulled the codes. Been out of town for the last couple of weeks - Backpacking with the Boy Scouts at Philmont, NM.

[DmaxMaverick]

OK, it finally acted up with me driving but in a different way.

Fired it up at the store after sitting for 10 minutes. Ran for about 10 seconds then died. Restarted but got a lot of diesel clatter for about 10 seconds. Took off down the road and even though I had pedal, the power was about half to a third of normal power. Could not maintain 55 and the more I pressed on the pedal, the more it downshifted trying to get up to speed. After a couple of miles, I decided to stop the vehicle and shut it down. After 10 seconds of key off, I restarted and it ran perfect again and has for the last couple of weeks.


This happened to my wife a few months ago and I dismissed it as just a freak event.

Still haven't pulled the codes. Been out of town for the last couple of weeks - Backpacking with the Boy Scouts at Philmont, NM.

Limp mode. You need to pull the codes, and find out why the PCM is causing it, or why it thinks you shouldn't have full power.