There seems to be a lot of OBD code threads around recently, I have another one. I have a persistent code of P1637 and P1643. This generates the "Reduced Performance" message along with "Transmission fault", "Cruse Control Not Available" and "Low Brake Fluid" messages.

The codes are associated with modules not talking to each other and I know the brake fluid is not low so at least some of the other messages are probably artifacts also. Does anyone know of a particular bad ground or connection or other cause I can test before I go to my dealer with the problem?

Thanks for any help.

 

The speedometer guage cluster is the communications 'hub', so you might want to inspect the two connectors (yellow and black) going to it and perhaps reseat them. Be sure to disconnect the battery if you plug or unplug these connectors.

 

Thanks WhiteXKR. I forgot that another message I get is "DSC unavailable" (That's probably important!) I supose the DSC module could have a problem.

 

Have you looked at your brake switch?

 

No I haven't Gus. This is the check to see if both switches are either closed or open at the same time? I will do that when I get home tonight.

Thanks
johnz

 

I think you have a power supply problem, probably associated with the fuse box over the LF wheel. Either a circuit inside the box or one of the relays in the box. A connection problem can momentarily take one or more modules off-line and set the comm faults. Try switching out some relays or jostling the box while the engine is running. You might induce the fault and confirm a fault.

Good luck!