Auto box doesn’t like the wet weather..

[Bongolian]

Hello folks, still pretty new to life with a Bongo and am suffering an issue with the auto box during wet weather..
Normally all is fine and it shifts through the gears as expected, however twice recently, on both occasions in really horrid rain, the box won’t shift up to fourth.
First noticed on a late night run across the M62 in monsoon type conditions, initially it seemed to rev like I’d missed a gear, so I gingerly reapplied the throttle and it picked up, but wouldn’t shift into fourth.
Back home and assuming water ingress I pulled all the leccy connectors I could see, sprayed and applied silicone grease before reconnecting.
The issue wasn’t seen again, probably as most of my trips were local and in decent weather.
However, my son borrowed it, again for a longer trip in heavy rain and he experienced the same symptoms, Auto box not shifting from 3rd to 4th.
Any Top-Tips, usual suspects etc.?

Any / all advice most appreciated.

[g8dhe]

You haven't by accident caught the Hold switch on the gear selector have you ? That should light the hold lamp on the dashboard (but its been known to have blown in the past!) but it will stop you go into 4th gear, also the gearbox needs to have warmed up it won't go into 4th for the first few minutes from cold.

[Bongolian]

Hello, nah I did try the button when it happened to me, no change, and indeed it would happily still change down to 2nd, but not up to 4th.
It had run along in fourth for some miles, but after the rain hit, and the speed dropped it would no longer shift up.
My son was driving it on the last occasion, again was running and changing normally, but after driving for a while in heavy rain it refused to shift up to 4th.
He said he backed off and kept the speed down but added it felt ‘lumpy’.
He returned home in the dry today and as before, the box performed perfectly.
I’m guessing the signal ain’t getting through to it to say shift, just need to pinpoint why.

[g8dhe]

The connector for all the main internal items comes out on the offside of the gearbox, might be worth having a good look down and follow the cable to the connector its roughly in the middle (not the red arrow!)

[Bongolian]

Thanks very much for the info/pic, I’ll have a deeper look and check it out.
Is this a ‘known’ issue.?
Or am I unlucky.?

Was wondering, I previously owned a Suzuki SV650 motorsickle, the front plug was criminally exposed to the weather on the early models so would cause issues as soon as the weatherman mentioned rain, had to be creative and fabricated a splash guard in the end, should there be a plate down there on the Bongo to offer similar protection.?

[g8dhe]

Not common from a wet weather problem. Solenoids that control the oil flow and gear selection is more often the problem but not from electrical problems.