Electrical - Idiot lights coming on, losing speedometer, RPM, radio. '06 Mustang

bren57

I have a 2006 mustang with 105000 miles. It recently started having issues with the airbag light, ABS, battery and TCS lights coming on and then all the others join in also. When this happens you have no speedometer , RPM, radio, heater . This stays like this for a few minutes and then they go out and all is normal. Maybe 20 - 30 minutes later is all happens again. The car is running fine and the headlights work. Last night I also noticed the headlights on bright stopped working. When my mechanic used an analyzer on it a few weeks ago nothing showed as a problem. Has anyone else had these problems and if so what was the problem?

thecardoc3

To analyze this accurately it really needs to be occurring while the tech is testing the car. It doesn't make any sense for nothing to have shown up unless the mechanic isn't using a full professional level scan tool. The manufacturer's strategy is if communication between the instrument cluster and a given system fails, the instrument cluster will turn on the MIL for that system and it will store a trouble code for the loss of communication. If a system detects a problem, it stores a code and commands the instrument cluster to turn on it's MIL, so when you see a warning lamp, at least one of the two modules should have set a MIL.

When you lose the tachometer, and speedometer again, that implies a loss of communication because that information comes from the PCM. Power for the heater, and radio have both the instrument cluster and the smart junction block as portions of the control circuit. The instrument cluster controls the accessory delay relay which provides power to the radio and heater controls.

It's highly probable that a failure is occurring in the instrument cluster, but power to it and operation of the smart junction block has to be confirmed while the symptom is occurring to prove that. Make sure you see out a shop that has the Ford IDS scan tool and is experienced with communication diagnostics as well as excels in electrical diagnostics and repairs to address this.