Where does the inst fuel readout come from?

someguy360 · Post by **someguy360** » Tue Aug 20, 2024 3:48 pm

Hi Gurus!

Hope everyone is doing well. I've got a quick wiring question for a VR with a 424 PCM.

I've just done a full wiring relocation/extension and new relay/fuse box on a VR (both body harness and engine harness) for an engine bay smoothing job. Everything is working ok except my inst fuel readout on the L3 cluster is showing 0 with the engine running. Distance to empty and litres used is working fine etc but inst fuel and avg fuel isn't updating.

I have some wiring diagrams for the PCM and sensors etc but none of them give a clear indication of what pin/sensor etc would be responsible for the inst and avg fuel readout on a L3 cluster.

If anyone could give me an idea of where I should be looking/tracing for this issue that would be amazing please. It's strange that distance to empty, fuel used, fuel gauge etc all works just not that one readout.

Thanks in advance!

ironduke · Post by **ironduke** » Tue Aug 20, 2024 10:34 pm

Just asking something really really silly.. Have you driven it yet? or are you just starting and running it in the shop??

Post by **Chr0m3** » Wed Aug 21, 2024 7:10 am

I don't know about that particular ecu but the later ECUs VX / VY etc calculate it and send it over ALDL to the cluster, I'd think it's the same but I don't know about that particular ecu as said.

pman92 · Post by **pman92** » Wed Aug 21, 2024 7:16 am

It's a 128hz PWM signal on pin A10

See here:
viewtopic.php?t=933

Deuce · Post by **Deuce** » Wed Aug 21, 2024 7:03 pm

I also suspect you need to do some km's on it for that reading to start working.

immortality · Post by **immortality** » Wed Aug 21, 2024 8:38 pm

Deuce wrote: ↑Wed Aug 21, 2024 7:03 pm I also suspect you need to do some km's on it for that reading to start working.

I think this sounds correct. I don't remember the VS showing fuel use at idle with the vehicle stationary like they do from VT onward.

Kevspec · Post by **Kevspec** » Thu Aug 22, 2024 7:40 am

Vs can show instant but u have to hold the mode button when you turn the car on from memory

someguy360 · Post by **someguy360** » Thu Aug 22, 2024 8:59 am

Thanks all, I found it was a loose connection on the pin A10 for the fuel input to the ECU, working again now, can see inst fuel readouts.

It definately shows inst fuel consumption on idle with the engine running and then starts working out average fuel when driving.

Where does the inst fuel readout come from?

Where does the inst fuel readout come from?

Re: Where does the inst fuel readout come from?

Re: Where does the inst fuel readout come from?

Re: Where does the inst fuel readout come from?

Re: Where does the inst fuel readout come from?

Re: Where does the inst fuel readout come from?

Re: Where does the inst fuel readout come from?

Re: Where does the inst fuel readout come from?