Logging control module voltage
Logging control module voltage 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
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.
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.
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.
So no, nothing to be concerned about.
. It's just odd, but if you don't think it's anything to worry about, I will check it off my list, 
. 
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Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
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.
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.
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.
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.
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
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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
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
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?
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