Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
2010 Volkswagen GTI 5 volt reference shorted to battery voltage?
Hello everybody. In the shop today I had a 2010 Volkswagen Golf GTI.
CEL is on, code is:
P2570 - Direct Ozone Reduction Catalyst Temperature Sensor Circuit High
OEM service information states this code is triggered when the 5 volt reference reads >5 volts. Three pin connector. Unplugged, both voltage wire AND 5 volt reference read battery voltage, ground on the third. With an OEM wiring diagram I tracked down which terminal on the PCM connector this 5 volt reference wire goes to. Unplugged the PCM connector, no bent pins which could've caused this shortage, no corrosion. Using a piercing probe I gently probed the wire. Nothing on the wire with key off, battery voltage on it with the key on. This is with the 5 volt reference wire probed less than two inches from the ECU connector. What other checks should I do before I condemn the PCM?
Battery voltage on a wire which is suppose to be at 5v, means pcm internal voltage regulator is not well connected to ground.
You should check first that all pcm grounds are connected to battery ground or chassi.
With voltmeter (negative test lead to baterry (-) and positive test lead to pcm ground/s), you shouldn't see more than 100mv (ignition switch on) neither more than 300mv (while cranking).
Topic Author
