Hart_Rod

iTrader: (3)

When I log control module voltage, it is consistently 1 volt lower than system voltage that my gauges read. Is that a problem? Is it normal? Should I be concerned? TIA

RonSSNova

iTrader: (3)

I'm curious as well.
ive seen mine as low as 12.5v while racing.
Normal seems to be 13.2 or so.
With the batt in the trunk, and the long alternator charge wire, I do have more voltage drop than I'd like to see. So I'm fixing that now.

MontecarloDrag

iTrader: (3)

What you see in a datalog is the voltage that gets to the PCM. However the voltage that gets to the cluster or another part of the vehicle won't be the same. Rusted grounds and connectors play a big part in this.
So no, nothing to be concerned about.

Hart_Rod

iTrader: (3)

Everything is new as this was a frame off restoration including all the wiring and I have run at least 10 different grounds . It's just odd, but if you don't think it's anything to worry about, I will check it off my list, .

mrvedit

I would check the voltage right at the PCM/ECM.
Is this a 411 PCM? If yes, Blue Pin 19 is ignition feed and Pin 20 is battery feed.
Also compare the voltage at the alternator and at the battery.
I had to run a 4 Gauge wire from the Alternator to get everything over 14 Volts.
It stated, it probably isn't an issue, but I like all the wiring and voltage to be correct.

Hart_Rod

iTrader: (3)

P59 computer. Battery and alternator voltage check the same (running and off). I'm running a Speartech Harness that has 4 fuses - battery, ignition, injectors and fuel pump.

When I check the voltage on the fuses with the engine running I get:

battery - 13.3V
ignition - 12.3V
injectors - 12.3V
fuel pump - 12.3V

Hart_Rod

iTrader: (3)

bump.

Jabjr26

iTrader: (4)

I have the exact same scenario i am working through right now on my rx8 LS swap. I have a speartech harness with the 4 fuse block, and with the car running i get:

battery - 14.5V
ignition - 10.6V
injectors - 10.6V
fuel pump - 10.6V

Its truly odd there is such a drop since im getting my switched 12V right from the ign relay in the rx8 fuse block. Did you ever figure out what caused your difference in voltage?