Charging problem

[Caseyrhe 650]

Pulled positive off battery while motor was running, engine died. That tells me it's not charging based on how I tested alternators back in the day. Had alternator tested--good, replaced voltage regulator, still dies.

Checked all wires on alt harness for condunuity- all good. Tach Mach, 4 wire alt, 4 wires going to voltage regulator.

What's next?

[1969_Mach1 333]

I've never checked charging systems in that manner.  I've heard of that.  But in my mind it opens the circuit so I wouldn't be surprised if something stops working correctly.  I would at least check the charging system voltage at the battery with a volt meter before condemning something wrong with the charging system.

 

Does the Alternator light in the dash still work while cranking?

[det0326 179]

I have seen charging systems checked that way and have did it myself back in the day especially when there were just generators and no EFi , expensive sound systems etc. You could probably get away with it too on a bone stock 69 mustang but if you have electronic upgrades I would be reluctant to try it because it could create a spike that could harm electronic devices. best thing to do is like 1969_Mach1 said is check battery voltage with VOM and if it is not around 13.8 to around 14.2 or so try increasing engine speed a little and if that voltage is still not there you defiantly have a problem.

 

 

Dave

[Midlife 814]

That method can also fry the diodes in the alternator.

 

If alternator checks out and VR checks out, I'd suspect a wiring issue.  Take it to Pep Boys or Autozone and they can do an in-body charging test and diagnose what's wrong.

[Caseyrhe 650]

No, the alt light does not come on, with the ign in on position or when starting.

Test light-

Has power to battery wire to alt

Does not lite up on any other wires off alt, when ign in on position

[barnett468 418]

is the alt wired correctly?

 

is the alt light bulb good?

 

unplug the regulator then bend a paper clip or wire and push it into the A and F terminals in the plug then check the voltage at the battery while it idles and then at around 2000 rpm and post results.

[1969_Mach1 333]

Hopefully its something simple.  But, he mentioned the Alt bulb never lights up, even during cranking when it should.  There should still be a 15 ohm resister wire that is wired parallel to the bulb, so I'm guessing when the bulb burns out the charging system will still work.  But, I don't know if it is a factory tach car or somewhere in its life somebody swapped out the instrument panel and didn't rewire the charging system correctly.  There are several wiring differences from a non-tach to a tach instrument panel so everything works correctly.  I guess there is an extremely remote possibility both the bulb and the 15 ohm resistor are bad.

[Midlife 814]

Hopefully its something simple.  But, he mentioned the Alt bulb never lights up, even during cranking when it should.  There should still be a 15 ohm resister wire that is wired parallel to the bulb, so I'm guessing when the bulb burns out the charging system will still work.  But, I don't know if it is a factory tach car or somewhere in its life somebody swapped out the instrument panel and didn't rewire the charging system correctly.  There are several wiring differences from a non-tach to a tach instrument panel so everything works correctly.  I guess there is an extremely remote possibility both the bulb and the 15 ohm resistor are bad.

Yes, it is a tach car (info from PM).  That's what I am thinking as well.

[jholmes217 65]

I had a similar problem with my tach car.  Turned out that passenger side headlight harness had a bad plug that was preventing a good connection.  That is the same plug that your alternator harness plugs into.  Check all your connections on the headlight harness, including where it plugs into the firewall.  

[Caseyrhe 650]

Midlife, see pics. Put meter on P and 5, nothing registered. P-3&6 also, nothing registered. Also, see meter, do I have it set right. Reread email after uncramping, fuse box clip?

[1969_Mach1 333]

Did the charging system suddenly quit working?  Did the alt light ever work correctly?

[Caseyrhe 650]

When I bought the car, motor was in, never started, rest of car in boxes. See 69 black Jade rebirth in project progress forum

[Midlife 814]

Aha!  You need to measure not between P and 5, but the fuse clip for ACC power on the other side of the fuse box.  P is battery power, not ACC power.  Your pin 5 is correct.  Furthermore, you're reading on the headlight side of the harness; I need you to measure on the underdash harness side (female pins).  The resistor wire is on the underdash harness, not the headlight harness which is where you are reading things now.

 

 

[Caseyrhe 650]

Meter read 1 before and during testing on harness side, pin to acc clip

[Midlife 814]

OK...that does it.  A 1. by itself means that it is an open circuit, with resistance higher than can be measured.  Your resistor wire is broken or not attached.  That and a bad bulb or bad trace on the circuit board will cause the Voltage Regulator not to be activated.

 

Ta-Da!  Houston, we have resolution!

[1969_Mach1 333]

I thought something was suspicious when the alt light didn't work.  I still wonder if the car was an original tach IP car or somebody didn't rewire it correctly when installing a tach IP.  If the latter is true, there probably isn't a 15 ohm resister wire wrapped up in the underdash harness.

[Midlife 814]

That is the main flaw of all of the Internet sites that describe how to convert a standard to a tach instrument panel. 

 

I had that resistor wire reverse-engineered by a specialty wiring company who then produced in a 2000 foot roll (minimum order size) that cost me well over $500 so that I could properly convert underdash harnesses. 

[Caseyrhe 650]

Dash pulled, bulbs all look good except RT blinker, which wasn't working. Tested condinutiy from fb pin to violet wire in pin 13 in dash cluster... no tone. Checked continuity from acc at fb on violet wire that was capped...we have tone.

Reading from acc to dash pin 13- ohm reader set on 200 reads 10.0.

From acc to capped wire- reads nothing

 

Dash pin 13 also has a black wire in it

 

It is a factory dash car

[Caseyrhe 650]

Circuit board is new also, Scott drake

[1969_Mach1 333]

That is the main flaw of all of the Internet sites that describe how to convert a standard to a tach instrument panel. 

 

I had that resistor wire reverse-engineered by a specialty wiring company who then produced in a 2000 foot roll (minimum order size) that cost me well over $500 so that I could properly convert underdash harnesses. 

I did a non tach to tach conversion a long time ago.  Several hours with both the under dash and engine compartment harnesses unraveled on my work bench and sorting through the wiring diagrams.  I had a hard time finding a resistor wire for the conversion.  A shop about 40 miles from me that repairs Mustangs and sell parts for them let me search through their surplus of used under dash wiring harnesses.  I found a factory tach harness and cut the resistor wire out of it.  Apparently, they didn't know how difficult it was to find that resistor wire since they gave it to me.

[Midlife 814]

For the record, there are two resistor wires, and I gave the OP misinformation.  The first resistor wire of 10.0 ohms, runs from ACC to the CVR input pin on the dash cluster.  The second resistor wire, specific to tach dashes or dashes with alternator indicator lamps, also runs from ACC power but goes to a pin on the fuse box connector that mates with the headlight harness.  Typically, both resistor wires start near the ignition switch: one at the pin itself and another at a factory OEM splice a few inches above the ignition switch connector. 

 

There's a third resistor wire of 1.5 ohms: the infamous pink resistor wire that chokes the coil voltage and current.

 

I'm putting my money on the idea that the ignition switch connector had to be changed sometime in the past, and this tach specific wire was not spliced back in or fell out of the crimp.  It cannot be soldered, and being a single wire strand, is difficult to crimp by itself.  It has to be reinforced with another wire segment when crimping; the other end of this section of wire goes nowhere, explaining the black wire on the dash cluster pin that is loose by itself when the tape is unraveled.

[Caseyrhe 650]

Robert, you are the man!!!!! Alt light comes on with ignition turned on and VM is letting juice go to the battery. With your help, my friend, those were the 3 easiest and cheapest 3 steps back on putting her back together. Many many thanks. And yes that is my happy face thumbnail!!!!

[Midlife 814]

You can call me Robert or Randy, but don't call be late for dinner!

 

You're more than welcome.  The best part of responding was trouble-shooting and finding the correct problem so it can be repaired properly.

[Caseyrhe 650]

Robert, the harnesses are headed your way. I already got my money back for what I paid from the parts car I disassembled. Your direction on finding and repairing my own wiring problems saved me a lot of stress and $$ in repairs.

Please except the harness at no charge and maybe use it down the road to help someone else out in need of a harness. Thanks again!!!

[Midlife 814]

Will do, but my name is Randy!  *G*