Normal ground resistance

[KnifeySpoony]

So I'm still trying to diagnose my part throttle misfire on my 420R. I went and checked continuity on various things - coils, injectors, sensors, etc. Using the continuity check on my multimeter everything was ok with a BEEP. However I realized that it will beep with anything less than 120ohms. So looking at the actual resistance, I noticed that all of the coil (and I think injector) grounds are consistent at 44ohms. Is this normal?

[KnifeySpoony]

FYI resistance was check with ECU plugged in, kill switch on, but car's ignition/power off. 

[Jonathan Kay]

Are you measuring continuity/  DC resistance across the component itself or from the component's earth connector to a good earth?

And were those resistance measurements with the components connected or disconnected?

Thanks

Jonathan

[KnifeySpoony]

I unplugged the coil loom plug at the Coil itself, then tested from the ground pin on the loom plug to the main chassis ground by the battery. For the other pin on the coil loom plug, I unplugged the ECU and tested at the appropriate ECU pin.

[Jonathan Kay]

Thanks

Jonathan

[aerobod - near CYYC]

I don't have the 420R wiring diagram, but on the wiring diagram for the R400 the coil packs don't have a chassis ground as such, but a common negative that goes to the MFU. With or without power there may not be a direct path to chassis ground.

[KnifeySpoony]

Ah ok i figured it was something like that given the consistent, but higher residence. What is the mfu? 

[aerobod - near CYYC]

MFU is the Multi-Function Unit containing relays that are not on the fuse panel, I'm not sure if all R400/420Rs have it, but the logic for engine start with a push button dash is controlled in that unit.

[Jonathan Kay]

Please let me know if you need any wiring diagrams.

Jonathan

[KnifeySpoony]

I am going on the wiring diagram in the back of the 2015 build guide which AFAIK is the most current published? My 420R is a 2021 build btw. 

[ScottR400D]

#8 James, I think only the R400/300/500 with the multi push button dash use that MFU, if you mean the board up under the dash (Instrumentation Circuit Board R500/Seven 485, part 39L059A)