Engine/Transmission (1998.5 - 2002) VA box intermittent failure

[M Campbell]

Hi all. I'm having an intermittent problem with my VA box. Three times now, after a cool night I've started up and headed to work, only to get a few miles down the road and the truck loses all power. It seems to go into some kind of limp mode where it will only run below about 1300rpm and it throws the check engine light. Each time I've unplugged the VA and put it back to stock and it runs just fine. After a few days I plug the VA back in and it works fine for a month or two. I took the box apart and can't see anything wrong visually with the circuit board. Well, a couple of the pins on one or two components weren't completely covered with the conformal coating. I've put a bit of silicone on those... Each time it has been after a cool night, so I was thinking it might be condensation related? I'm going to try mounting it vertically this time just in case somthing was dripping in there. Also, has anyone used the 9-pin connector on the board to interface with it?



Thanks for any suggestions.



Mike



'99 QC 4x4, VA, PS Boost Module

 

[Jetson]

Do you have a boost module, or does your VA have a plug that plugs into the MAP sensor? If so, you probably have a bad connection at the MAP sensor. The computer reads boost before it sends fuel. No boost signal, no fuel, no power. Check this first and put some dielectric grease on the MAP sensor connectors.

 

[DMarriott]

Could be condensation. I had some trouble with mine a couple years ago when I would wash my Engine. I took it apart and sealed it with some Silicone. Never happened again.



Don Marriott

 

[M Campbell]

Thanks for the reply guys. Jetson, I have a Practical Solutions boost module. The truck runs fine with just the boost module installed... even when the boost goes over 18 psi. I sealed the gaskets up with some Hylomar as well as put some silicone on the few exposed leads of a couple of parts on the board. Hopefully that plus mounting it so any drips run down the frame inside instead of onto the board will cure it. I've got a funny feeling that it may be a bad component though... .



Thanks Again,

Mike

 

[Jetson]

I sealed my VA box with silicone at the seams because I had heard that water would get into it. I was using a Practical Solutions boost module also. I took it off sometime after I added the Edge 3 level box. I still run the VA and turn on the Edge box occasionally.

 

[M Campbell]

Thanks for the reply guys. Jetson, I have a Practical Solutions boost module. The truck runs fine with just the boost module installed... even when the boost goes over 18 psi. I sealed the gaskets up with some Hylomar as well as put some silicone on the few exposed leads of a couple of parts on the board. Hopefully that plus mounting it so any drips run down the frame inside instead of onto the board will cure it. I've got a funny feeling that it may be a bad component though... .



Thanks Again,

Mike