P2670 & P2671 - where's the earthing for 5v circuit?

[Wpug308]

Hi all. Car is 2011 308 SW 2.0HDI. I've got an engine light on and aircon has stopped working (compressor clutch doesn't engage). I scanned for codes and I'm getting a host of sensor error codes which I'm guessing all share the same 5v supply: aircon pressure sensor, DPF pressure sensor, turbo repeat sensor to name a few. I also get P2670 and P2671 which state "5v supply voltage too low" and "too high" respectively. I have rashly replaced a few sensors as well as the Delphi DCM 3.4 engine ECU with a cloned one after following advice from a local garage, but this didn't do anything. I am thinking it could be the earth for this 5v supply but I have no idea where it is located to check it and clean it in the hope this might solve the issue. Can anyone offer me some advice on this issue and/or the location of the earth point? Thanks in advance. Cheers

[GiveMeABreak]

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[Wpug308]

Hi. Thanks for your reply. VIN is VF3**************[VIN obfuscated, can be read by forum staff]. Thanks!

[GiveMeABreak]

Fault Code:	P2670
Description of Fault:	Supply of sensors 5 Volts n°2: Voltage too low. Voltage supply to the sensors is lower than 4,7 V for more than 5 seconds (Turbocharging pressure sensor; Air flow meter sensor; Particle emission filter pressure sensor; Turbocharger position copy sensor; EGR valve position repeat sensor; Air conditioning pressure sensor).
Conditions for Fault to clear:	Ignition on
Downgrade Modes whilst Fault is active:	Torque limitation for traction control Deactivation speed limiter until the next time the ignition is switched on Deactivation cruise control until the next time the ignition is switched on The ECU stops the regulation of the EGR valve The ECU limits the fuel flow Deactivation of the closed loop of the turbo regulation (Piloted turbocharging mode) Switching on of the warning lamp and/or warning message: Warning lamp MIL
Symptoms:	Jerking/stalling Lack of power Starting problem
Suspect Areas:	Sensors sharing the supply Electrical harness Engine management ECU (internal failure, supply, ...)

Fault Code:	P2671
Description of Fault:	Supply of sensors 5 Volts n°2: Voltage too high. The sensors supply voltage is higher than 5,25 V for more than 120 milliseconds (Turbocharging pressure sensor; Air flow meter sensor; Particle emission filter pressure sensor; Turbocharger position copy sensor; EGR valve position repeat sensor; Air conditioning pressure sensor).
Conditions for Fault to clear:	Ignition on
Downgrade Modes whilst Fault is active:	Torque limitation for traction control Deactivation speed limiter until the next time the ignition is switched on Deactivation cruise control until the next time the ignition is switched on The ECU stops the regulation of the EGR valve The ECU limits the fuel flow Deactivation of the closed loop of the turbo regulation (Piloted turbocharging mode) Switching on of the warning lamp and/or warning message: Warning lamp MIL
Symptoms:	Lack of power
Suspect Areas:	Sensors sharing the supply Electrical harness Engine management ECU (internal failure, supply, ...)

So here's the injection wiring diagram for your specific vehicle with this engine ECU:

With the exception of the wiring codes, most of the component codes are indexed here:

PSA Electrical Diagrams - Wiring & Symbols Codes Index

From the looks of things all these relevant sensor connections, including the earths go back to the engine ECU itself, so it may be one of the earths from the ECU itself.

MC10 and MC12 should therefore be looked at. The first diagram shows the earthing points on the vehicle. But as both of these earths from the engine ECU in question are connected to the 48 min maroon wiring connector, I would also check the quality of the pins and wiring of the actual plug itself, as this won't be the first time there has been loose pins / wiring to the pins on the connectors.....

[Wpug308]

Hi Marc, thanks so much for all this info. It is mega helpful for me. I will have a poke around this weekend and see what gives and let you know how I get on. Thanks again! Winston.

[GiveMeABreak]

No problem, good hunting!