What does B+ voltage mean?

[Justin]

I had to make a repair on my van today p1512 intake runner stuck closed bank 1. I did alittle clean up/ rod bushing replacment and well it was a eletric problam I love this kinda problam after haveing a problam last winter I had to rewire from computer to map sensor alot of joint connections too. Ref 5v sig ground yeap I dreamed it. I learned to sodilder pretty good in tight places too. well I made a lucky easy today on the intakerunner stuck well the 3rd terminal was opened more then it should have been I fix terminal and got good contact and fix it the code cleared self. I didn’t get to this part of the voltage test on harness it asked is there B+ voltage at terminal 2. What it B+ voltage what does this mean? I seen this before when doing my map sensor repair but couldn’t find what it means. any idea

Thanks
Justin

Topic

[Austin]

I would assume that’s talking about the circuit. I’ve seen it on things like TPS that go bad EGR, etc. Circuit A low, things like that.

[Wayne]

It’s a hold-over term. In modern circuits it’s meant as the high voltage bus in relation to the device. It’s just a term that’s held over the years from the earlier days of electronics with vacuum tubes using batteries.

[spelunkerd]

As stated by Wayne613, it’s an old term. On a starter motor, the B+ post is the one directly connected to the positive pole of the battery, always hot.

[John B Kobberstad]

B+ is the voltage found at the positive terminal of the battery before any voltage drops reduce it.

[JOHN SHORE]

B+ IS “BATTERY VOLTAGE” WITH RESPECT THERE SHOULD BE “NO” VOLTAGE DROP. VOLATGE DROP IS A FAULT
JOHN

[Lorrin Barth]

Wires have resistance. Overcoming resistance takes energy and that causes a voltage drop. On a thick cable the voltage drop will be close to zero. On a small wire going all the way to the rear of the car it could be a volt or more.

[Tom]

B+ voltage refers to the voltage found at the positive terminal of your battery. With the engine off, this is typically a bit over 12 volts positive, engine running it should be more like 14.4 volts.

[Justin]

Thanks for all the replys it make snice B+ voltage is same as your battery pos+ because it ask when I rewired my map sensor if terminal C was B + voltage. How you tested it was put your neg multimeter prob on that terminal and pos + lead to pos+ battery to see if it was the same voltage as battery. I get it now I remember how starters B+ post and voltage thing. I was just thinking to hard about it lol

Thanks again

[JOHN SHORE]

ALWAYS REMEMBER, to do a “voltage drop test” current must be flowing.
John

[Author]

Replies