DME Voltage Drop
 

Hey All,

So ive been trying to identify why my DME "Supply Voltage" reads around 13ish Volts but the voltage on battery is around 14.3, on my 2004 986 2.7 M96.23

some symptoms:
- Random ABS/PSM Light on
- Huge struggle whenever radiators, AC are on
- Random idle struggles
- Remote key not working (new remote - dealer programmed it but no luck)

Ive already replaced both DME relays but no luck. Next step i guess is the DME Ground point but other than this im out of ideas.

Thanks as always :cheers:

So under electrical load or when at low RPM there is a problem. Have you looked at the charging output? Battery load test?

Yes but the voltage is always lower in the DME. Plus when i activate AC for example, the DME Voltage almost stays intact but it shoudlnt (afaik).

1. Alternator and VR are new.
2. Battery is 2 y.o and "seems" pretty good
3. Engine ground strap is new
4. Throttle body is new
5. No CEL

I believe that something (corrosion?) is dropping the voltage and DME doesnt see any spikes/drops and thats why it cant "correct" the RPMs on time.

I checked the voltage on both the DME relays (Pin #30) and both were showing around 0.3V lower voltage than the battery.

Also measured the C1 fuse voltage and it was the same as the battery. So i guess it may be an issue from the FUSE Box back to the relay ?

Are you measuring the actual voltage or reading it with Durametric or some other device?

Yeap im using my multimeter for this. Initially i found the problem using my iCarSoft reader and now testing with multimeter and the results are pretty much the same.

For now its "Acceptable" but if the voltage drops more then all sorts of issues may arise (i.e injectors?). Obviously changing the entire harness is a no go :eek:

Not sure if this can be continued as a DYI tbh so maybe its time for a good electrician