yjyerks

I am currently servicing our 2001 mack cl700 with the cummins 600 engine, we keep getting the wrench light but when i actually have it in the shop to check the codes the light is no longer on, The truck has had a rough idle all year, once in a while it will stall, but mainly we will be driving with a load and it will slow down in a limp mode and the wrench light and electrical malfunction light come on. Any suggestions would be great.