2.3L 2007 Mazda5 Wiring Diagram - No 12V on alternator Sense lead

[atw58]

The alternator is not generating any voltage to the battery according to my meter. The alternator B terminal reads the battery voltage (11.5V) and nothing if the cable is disconnected when the car is running. I removed the 2 wire clip with Sense (battery voltage) and L (battery dash light). There is zero volts on the Sense lead when there should be 12/14V.

Can someone direct me to the charging system wiring diagram. Searching the internet was not useful.

 

[negusm]

Are you in the US? Any big box auto parts store will test an alternator for free. I'd go to Autozone or Advance Auto.

I'm assuming the alternator has an internal voltage regulator...so nearly all the charging system is in the alt. Much older cars would be separate.

 

[negusm]

ok, yeah, rereading this.

The Sense Wire should go straight to the battery as it tells the alternator what voltage the battery is at and nothing should really be in between the battery and the alternator for this connection.

Usually...on issues like this...suspect the cable and terminal at the battery. With the car off, I would first check continuity from the alternator sense wire connection to the battery. If none, then I might try jumping a wire from that connection straight to the battery and seeing if the alternator starts working with the car on.

Then track down that sense wire and where it is broken. Usually at/near the battery terminal.

It's a really simple setup usually. 3 or 4 connection. Positive, Ground, and Sense and maybe tach.

While I haven't dealt with it on this car, I have on others.

If you really want a wiring diagram...I always recommend the Service Manual which has it. Usually electronic copies can be found on Ebay for $10. Be prepared to stare at it and decipher the codes/symbols but it WILL tell you EVERYTHING.