Alternator not charging
Customer supplied alternator installed but not charging. Having problems finding service data on system operation but have 2.5V square wave that slowly transitions to flat on the blue wire and no voltage on grey wire at alternator connector or PCM. When unplugged at alternator blue wire rises to 8V with no voltage on grey. Checked continuity of wires and they were good. Read some identifix articles and looks like both wires at alternator should show voltage with one wire having a square wave but would prefer actual service data or well informed advice.
At idle terminal P should be 3-8v (backprobing). Terminal D should be approx. 0v ignition on and voltage should rise at idle when loads are applied.
Also check pin retention at alt. plug. These are known for getting loose.
I've not had any luck with aftermarket alternators in these. I'm not sure you can even get new OEM, but the dealer rebuilds are pretty good. I did have to fight when one went bad in a month.
Can't help with the diag, other then to say that I hope you are getting paid well for any additional diag, beyond the r&r of the customer supplied part. If you have other work to do for other customers, this one is costing you by the minute. Just saying
…Letting the customer furnish the hardware is in direct violation of the policies in place at my garage… I would send him down the street … Dan H.
A 2006 Mazda “should be” similar to Ford. (GenMon and GenCom) What codes are setting in the PCM? If I am correct about the Ford system overlap with only the main alternator output connected and the voltage regulator disconnected it should self excite over 2000rpm and start charging at a failsafe of 13.5v approx.
Customer supplied warranty alternator after having me call rebuilder to confirm diagnosis. Replacement is creating a 8v square wave to the PCM plus the signal that was being generated previously. Safe to say that this system is the same as Ford.