Scanmaster Voltage reading question

[Rich Gio]

After a few runs at the strip last night I noticed voltage readings of 12.4 to 12.8 on the scanmaster. My question is : Since I hotwired my fuel pump off the back of the alternator and the ignition is hotwired off the battery (With the caspers kit) does this lower reading on the scanmaster really matter?

 

[Jerryl]

After a few runs at the strip last night I noticed voltage readings of 12.4 to 12.8 on the scanmaster. My question is : Since I hotwired my fuel pump off the back of the alternator and the ignition is hotwired off the battery (With the caspers kit) does this lower reading on the scanmaster really matter?

The “reading” itself doesn’t matter, if it is inaccurate.
If it is accurate, it DOES matter.
When did you start seeing the low voltage?

 

[Rich Gio]

The “reading” itself doesn’t matter, if it is inaccurate.
If it is accurate, it DOES matter.
When did you start seeing the low voltage?

Recently, as in last couple days, when the car is hot it usually reads low 13ish. I AM reading 14 at the back of the alternator and at the battery, though.

 

[dpasadena]

Recently, as in last couple days, when the car is hot it usually reads low 13ish. I AM reading 14 at the back of the alternator and at the battery, though.

My scanmaster readings were a lot lower than the voltage at the alt. I replaced my ignition switch and the scanmaster now reads the same as the alt. I thank Steve Wood for helping me with this problem. Apparently over time the ignition switch might fail to make a good connection and the voltage can suffer to the fuse box.

 

[TurboBuRick]

Take all accessory load away from the factory fuse panel. Run a aux fuse block with a relay for all accessory's.

RL

 

[Nick Micale]

Check out this thread:

http://www.turbobuick.com/forums/threads/voltage-variations.378211/

 

[Rich Gio]

My scanmaster readings were a lot lower than the voltage at the alt. I replaced my ignition switch and the scanmaster now reads the same as the alt. I thank Steve Wood for helping me with this problem. Apparently over time the ignition switch might fail to make a good connection and the voltage can suffer to the fuse box.

I will troubleshoot shortly to find exactly where the voltage drop is. I'm just curious if it matters due to my ignition AND fuel pump being "Hotwired". Anyone?

 

[williamsGN]

As long as the pump is getting 13+ I believe you are fine. Other components on the car can run around 12 volts which is all they need to operate properly. Mine reads about a volt lower at the SM than at the alt/battery.
The scanmaster is seeing what the ECM is getting voltage wise, not the pump. I actually ran a wire from my pump wiring into the car so I can confirm voltage with a meter when on the road.

 

[Rich Gio]

As long as the pump is getting 13+ I believe you are fine. Other components on the car can run around 12 volts which is all they need to operate properly. Mine reads about a volt lower at the SM than at the alt/battery.
The scanmaster is seeing what the ECM is getting voltage wise, not the pump. I actually ran a wire from my pump wiring into the car so I can confirm voltage with a meter when on the road.

That's a great idea!