Please help - Volvo iShift, no throttle response

New update* the cruise control was not working this morning on the freeway, so while I was trying to diagnose the issue, I pressed down on the service brakes and then the cruise control started working. I'm assuming this issue would be caused by a faulty brake switch. Any advice or alternatives would be greatly appreciated.

 

Micro brake switch could be out of adjustment.

 

My truck is doing exactly what you have described, I have had the Volvo tech s run diagnostics twice and it’s indicating problem in I-shift electrical harness so where, I have taken the truck to Volvo service centre Monday and they are still trying to fix today (Thursday) I will let you know what the fix ends up being if they actually tell me what the real problem turns out to be. The clutch and I-shift transmission where both showing very good life remaining when they ran the calibration so hopefully they don’t just throw in a new transmission. My truck was ok for first hour of the day but then the problem would start exactly as you described, if the problem randomly occurred while slowing down using engine braking the engine brakes would also cut out and engine would reduce to a idle. Sorry cannot offer what the fix is but will try when truck is fixed. I have read other posts with same issues but a fix was never posted...

 

Ask the dealer to perform a test drive while monitoring parameters. Saved me so much time and money. If it happens more when loaded then ask to hook a trailer and monitor. Don’t let them just continue to run idle diagnostics. $$$

 

Yup! The micro brake switch spring had a lot of play when removed it so I just replaced it and it works perfectly now! Thanks for the help!

 

Hey hey, did you get it fixed, having identical issue, would like to know where to start looking?

 

Did you find the issue I got the same problem

 

I replied to 8withaV that the
Micro brake switch could be out of adjustment. After replacement their issue resolved. Check that out first and keep me posted