Can anyone enlighten me to what the switches in the picture are… loathed to touch em till i know what they do… but they keep enticing me to press… 
Top one kills white smoke but I’ve not noticed it do anything on mine and the bottom one will be for the exhaust brake at a guess.
ah ok cheers for that, out thats to bed. nothing exciting then… booo 
Yep top one reduces emissions bottom exhaust brake i keep em both on
Sits back and watches passenger fly over head 
sweeper1gg:
Yep top one reduces emissions bottom exhaust brake i keep em both on
1 of our fitters told me not to keep that top one on , you can hear the difference in engine tone when it’s on but like someone else said it doesn’t seem to do much lol
It only kicks in when braking, well driving a bulker you need it to stop.always max weight.
The top one is to reduce emissions when running the engine inside ie on a ferry or in the workshop and shouldn’t be used for everyday use best kept off, the other is your exhaust break and should be applied for the majority of the time tho not to clever when on the bounce or out in snow and ice
Judging by the state of them as in unclean I wouldn’t touch them or anything else in there without a tetanus jab or at least surgical gloves!
White smoke limiter (top one) also helps heat engine up when cold!
Shoshaye:
Top one kills white smoke but I’ve not noticed it do anything on mine and the bottom one will be for the exhaust brake at a guess.
Which you will have noticed doesn’t do anything either!!
nick2008:
Sits back and watches passenger fly over head
Don’t laugh, we have several Swedish Bedfords that deliver to my place that look so totally ridiculous I’m sure they must have button on the dash which causes the doors to fall of with a loud flash bang and a load of smoke, and the drivers must throw shaving foam pies at one another.
Retro rob:
Judging by the state of them as in unclean I wouldn’t touch them or anything else in there without a tetanus jab or at least surgical gloves!
I can’t see a problem.
Retro rob:
Judging by the state of them as in unclean I wouldn’t touch them or anything else in there without a tetanus jab or at least surgical gloves!White smoke limiter (top one) also helps heat engine up when cold!
Do you wear a full hazmat suit when venturing outside? its a bit of dust ffs
Top one is the white smoke limiter for use on cold starting. When you fire up on tickover it spplies a little exhaust brake load to increase load on the engine and limit unburnt fuel. As soon as you release the handbrake it is disabled. The lower one is exhaust exhaust brake on or off. Works in conjunction with the foot brake.
Top one is usually only switched on when starting cold.
If you get a chance read through the Scania driver’s manual.
It’s all in there mate 
FLIP:
Top one is the white smoke limiter for use on cold starting. When you fire up on tickover it spplies a little exhaust brake load to increase load on the engine and limit unburnt fuel. As soon as you release the handbrake it is disabled. The lower one is exhaust exhaust brake on or off. Works in conjunction with the foot brake.
Top one is usually only switched on when starting cold.
If you get a chance read through the Scania driver’s manual.
It’s all in there mate
your assuming i have a manual i did look for one online but could find one so thought id ask.
thanks all for your help much appreciated
Top one is wired up to the tacho.
nah the one wired to the tacho is normally hidden under the ashtray!
Just wondering about the auto button under the retarder on the 4 series Scania should that be on auto all the time as well and how should the retarder be used is it pull straight through the 5 stages or one by one leaving a few seconded between each level
Doesn’t matter how you use the retarder, just use it as much or as little as you want. The auto switch just applies the retarder & or the exhaust break automatically depending on how hard you press the foot brake. It will also apply if you go over the set speed if it’s on. Been a while though.
Sound but if the retarder lever is left down like at stage 5 when driving it seems like the trucks been held back I think