Random Electrical Issues

[FiestaBob1968]

My Fiesta has a strange electrical problem. The car will jerk and the Service Engine Now light comes on. I read the codes, clear them and the issue is resolved. The strange part is that the codes are different. I’ve gotten low voltage to the ABS module, night voltage to the ABS module, TPS stuck open, Low power to the airbag module, high voltage to the airbag module. Also, there have been issues with the alarm going off randomly. I’ve replaced the battery and the negative battery cable. Since my son drives this across the state in mountains, I really want to get this fixed.

 

[Handy Andy]

The negative battery cable may not be the problem, a loose electrical connection either at the batteries' Red terminal or grounding point - I know of three in the engine bay - two by and below the brake booster on the rear engine firewall and a 3rd at the lower left frame to ground the front fan - along with the headlights and some sensors.

Again, this sounds like a loose connection and it can even be from the multi-terminal connectors on the kick-panels - where the main feeders from the front snake into the passenger compartment and go to either side and they bolt down to hold them in place and keep pressed together.

Considering you have to take the interior apart - might want service to do this - for it can be as mess when the plastic parts break.

You live in mountains, check for mice - they can wreck you car by eating it alive.

 

[FiestaBob1968]

Hello Handy Andy. Thank you for the information. I suspected it was electrical. The mechanic was not happy that I cleared the codes, even though I gave them a printout of the codes at the time. I’ll check on the connections as soon as possible.

 

[scotman]

My go to tools for cleaning ground connections. Unless you live in New Mexico, Nevada or Utah it’s something that every Fiesta needs to have done to it to prevent the glitches from turning into a failed BCM or Capacitor. Too much voltage is bad, everyone except for very ignorant people know that. But too little voltage or erratic voltages on circuits that are carrying CANbus signals is also bad. The voltage requirements are low for CANbus circuits but they are very specific and must be stable voltage to carry the signal.

 

[FiestaBob1968]

Thanks for the picture of the toolset. Since you mention some dry areas, I assume you’re thinking moisture. We’re not much wetter here, but enough so that I’ll need to check the cables for corrosion.