This is a 2004 ISL 400, it has a 2 stage Jake Brake, not a Pac brake or exhaust brake. There are 2 solenoids inside the valve cover that activate it. On low it only uses 3 cylinders for braking, on high it uses all 6 cylinders.
When I first got this coach, the Jake did not work at all - found that out on Red Mountain Pass. After that adventure, I dug around and found the plug for the rear solenoid behind the AC compressor was not plugged in. I plugged it in and now have 1/2 brake power - or the equivalent of low. No matter if the switch is on high or low - same brake power.
I decided to try and find the other one - near the transmission end of the motor. I found it and that connector is plugged in. I got a long screwdriver on it and moved it around to be sure it is making contact - seemed to make no difference. It's the small right angle connector plugged into the side of the head.
I followed the wiring down to an area above the starter and found a couple of plugs that look suspect. They are both 2 wire and look like they might connect together, but they are zip tied off so they can't reach. I would have to cut the ties off and try them. It's very hard to get to this area - I had trouble getting a picture. The female appears to be at about top left in the picture, male is at center right.
I think the male may be coming from the Jake brake wiring, but I'm not sure.
It has a jumper crammed in it - see below.
Is anyone familiar with the wiring in this area?
I may be able to get in there to try putting those together but I have a couple of concerns:
1. I'm probably going to hurt myself getting in there. I took there pictures from the air cleaner looking over the frame.
2. If those don't belong together, I could cause some trouble.
I have adapted to driving with a weak Jake - but would sure like to have the full effect.
Thanks, Tim
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