I have an 04 ltd that goes berzerk until fully warmed up. When I start it the first time for the day, after 1-5 min, the spoiler raises, speedometer quits, brake light, check engine light, etc (BAS & ESP light has been on now for several months) come on and trans is put in limp mode. Once the car has warmed up for 15 min or more, turning it off and restarting clears the problem until the next day (days are not that cold in Calif). My code reader shows P0720 & P0600 and I delete them and of course they come back the next day I start the car. I already tried replacing the (original!) battery. Anyone else resolve this issue or have any ideas? Help would be greatly appreciated.

 

P0720 Output Speed Sensor Circuit Malfunction

P0600 Serial Communication Link Malfunction

check all the plugs you can find they may be loose or dirty,, maybe sombody can tell u where these sensors are maybe they are shorting out or Wet jim

 

all connectors, fuses appear fine. Sent RCM in to tighed1 (thank you!) to have it resoldered - no joy. Anyone have any ideas??? Thanks for the help.

 

The cause of ALL my issues was the ABS/CAB unit. I picked up a used one ($90), put it in, and now everything is working properly with no lights or codes! The stealership wanted $1600; $1000 for the part (which they said was on national backorder with no date in sight) and $600 labor. It took me an hour to jack up the car, remove 4 wheels, replace the part, and then another hour to bleed the brakes.

 

Age/condition of the battery?

 

Did you bleed the brakes the old fashion (with a helper pumping the pedal) way? Just curious, I use a brake vacuum but can't get the pedal feel how I want it.