pcmhacking.net

Hey All,

I'm the last stages of my custom dash and now moving onto some of the smaller items that need to be finalised, the one I'm currently on, which is the fuel gauge.

My car is an 85 Pontaic TransAM with about 90% of the wiring removed and replaced with a VX/VY commodore nervous system, i.e. Body harness, dash harness, LS1 PCM and harness, and the BCM and dash to boot. This was also coupled with a 1999 Firebird fuel tank which uses the same level sensor as the VY commodores.

The ABS/SRS warning lights were giving me the shits, and the cluster was failing anyway, so I deicded to bite the bullet, completely remove the dash and start on a new one that displayed all my speed/revs/and the rest of it on an Android Tablet via DashCommand, and then get the fuel level through that software.

The PCM has the fuel signal in wire, on Red Pin 53/54 (seems to be some variations from model to model) but I wasn't able to find a ground reference input for this.

My problem though, is that without the gauge plugged in, I don't get any reading from the return signal.
Looking at the circuit diagram for the cluster, it seems X1-29 is the voltage for the signal, and X1-19 is the return signal for the ohms reading.

I know the PCM can take the signal and send it through OBD2 as this is how the 99-02 LSX firebirds in the states do it, but I'm wondering how I power the level sensor without the cluster attached?

Current Dash for reference
https://youtu.be/izsWft_RGZY


https://forums.justcommodores.com.au/th ... am.264368/

you can program all the abs bullshit off. i did that for my drag car. from memory it was via masking the abs in the cluster & programming the bcm as a no abs setup config.

Tre-Cool wrote:you can program all the abs bullshit off. i did that for my drag car. from memory it was via masking the abs in the cluster & programming the bcm as a no abs setup config.

LOL, I'd asked many people about doing that and everyone replied it couldn't be done without emulating the abs module etc.

Oh well, too late now.
the dash is done.

I think I can sneak a 5v reference/supply voltage from the A/C or fuel pressure sender to power the level sender and that should then return the ohms to the PCM and send across.

I've done it heaps of times for race cars, who told you it couldn't be done?

From memory I think it was Tazzi. That may have been that it was not possible with his software, but I had never heard of the option of reprogramming the BCM and/or gauges.

I think the new dash is better than the VY cluster anyways
https://youtu.be/g69EuGMO1MM

Holy S**T well done on that! Space ship spec.

antus wrote:Holy S**T well done on that! Space ship spec.

haha, yeah I wanted something between KITT's 80's dash and a Tesla.