Battery not charging

[SmallTires]

So my on going headache of a car has given me another issue now. The vehicle is an 86 mustang GT. The battery will not charge to save my life. Alternator is a new unit I purchased. Battery is new as well. Is there a testing procedure I can follow to figure out where the wiring problem is in the system? I am beyond frustrated at the moment.

[Domino]

First check the condition of the alternator plugs. They are notorious for burning and corroding. On the rectangular plug you should have two big black wires. Those should both be battery hot. On the oval plug there should be two wires as well. The green wire with the red stripe is hot with the key on. The other wire I believe is yellow and it is battery hot. I don't believe the 86 harness has the stator wire like the 87-93s did.

[bwguardian]

I can't remember if the 86 has the external regulator like the 85 does. I had a simular problem where I had an altenator go on me and I replaced it. Battery would go dead after a short drive. I replaced the external regulator and problem solved. Well, I guess it took a toll on the battery because it went south shortly afterwards.

[grabbergreen84]

Check all of youre fuses early on in this hunt, too. There is at least one fuse, which if blown, will cause a no charge.
There are also fusible links for the charging system, which are under the hood.
Check the Wide Open Throttle relay as well. It cuts off your AC compressor and, I'm pretty sure, the charging circuit during WOT.



I had a mystery no-charge on my old '84. I'd taken off the factory carb to rebuild it, and stuck a spare Holley 600 on there so I could drive it in the meantime, but it wouldn't charge. I ended up wiring up my own charging circuit, and never figured out the problem until after my factory carb was back on there, with its WOT switch. I didn't have this problem on my '82 after switching carbs and ditching the WOT switch.

[SmallTires]

Well I got the new alternator in, as I said nothing. It has a third wire which I am not where exactly it should hook up as I cut the old melted harness that only had two wires that were black and orange. Also I have some sort of missing ground on the passenger side fender well. I have pictured both. Unfortunately this drained my brand new battery and now I need to figure out a way how to recharge the thing now. I am two steps away from getting some gasoline and a match with as much money as I have put into this thing the last month.

[Domino]

That white wire is the stator wire and it is not used on the 86. I don't know what would go on that screw. There are no grounds in the harness there. If you do not have a charger for the battery you can take it to any of the auto parts stores and have it charged for free. If you are having charging problems and you have checked the wiring it only leaves the alternator. If the green wire has power with the key on and the others are battery hot it is probably not a wiring problem. Is the alternator making a field? You can check this by holding a screwdriver behind the alternator. If it is magnetically pulling it towards the alternator there is a field and it should be charging.

[86GreenStang]

Upgrade that fire hazard to a 3g. The 2 B/O wire splice together and connect to fuse links B, C, and D (all black fuselinks) also the B/O wire feeds the ammeter across the shunt. White wire is not connected. Y/W splices to B/O wires a fuse link splice. LG/R is hot in run from ign switch.

[Domino]

Did you ever get your charging problems figured out?

[SmallTires]

I was just about to reply to this. So some issues have arisen. First the new battery I bought was drained so low it needed to be warranty replaced. So I am still awaiting on that which it should be here tomorrow. Also my voltage reader was junk so I needed to get another one of those. Also upon inspecting the wiring harness after looking over the diagram I found two issues. First it appears that one of the fusible links, specifically the one for the ignition the blue one has been cut out all together. Also the prior owner had an issue with ignition and rather than fixing it jumper the wire from the key on the steering column to the starter solenoid directly. It would explain why the column had been changed in the car to a fox body cougar column with cruise control, which my vehicle doesn't have. My guess is he tried to fix the wiring problem, when it wasn't simple he replaced the column entirely. When that didn't work he just jumper the column to the solenoid. What a mess. As stated in a previous thread, my understanding is that a cruise control column and none cruise are different in wiring. If I am correct this maybe one of my issues. Problem is there are no fox bodies around my area that are similar year without cruise. Every single one of them has it. Any insight would help. Also where can I find a replacement for a missing or damaged fusible link for these cars that is new, rather than just trying to hope you find a good one in the junkyard? Pictures below. The first is the missing fuse link in the wiring. The second being of the brown jumper wire from the column.

[Domino]

The columns are the same except for the cruise circuit. Fusible links can be purchased at your local parts store with the fuses. If there is a wire jumpered from the column to the solenoid I would bet there is a break in the start circuit some where. It is probably attached to the white wire with a pink stripe. Do your backup lights work? Your transmission harness may be damaged. Can you get pics of the hacked wiring? That fusible link is probably a good part of your charging problems. By the way, the gauge in the dash for charging is often bad in these cars. My alternator charges at 14.2 and my gauge never moves.

[SmallTires]

I needed to replace the reverse light switch and harness on the vehicle. I have gotten both, a new switch from late model restoration and good harness section from an 83 mustang gt. The section of wiring between the switch and the main harness. Could this also give me issues? Both of these were pretty well destroyed prior to my reception of the vehicle.

[Domino]

If it is damaged it will cause the reverse lights not to work and it will cause a break in the start circuit. That is most likely why there is a jumper from the column to the solenoid. If your car has a manual transmission this also means the clutch switch is bypassed and it will start in gear and could be dangerous if someone is unaware of this.

[SmallTires]

Yeah, they did jumper the neutral safety switch. Trust me I found out in an unpleasant way. Thankfully nothing was around and no property or persons were hurt. If what you said is the case and I repair all of this it may finally start without the jumper wire. Which would be great. Though this still doesn't fix the issue of why the battery is not charging. I will have to wait till tomorrow when the new battery comes in to check for voltage issues. This is becoming a fairly large headache.

[Domino]

I am one of the weird people that enjoys this. I like finding all of the solutions for things just like this. Like I said earlier, if the green wire with the red stripe is hot with the key on and the other wires are hot all the time then your battery should charge. Once you get it running try the screwdriver trick I mentioned earlier. If the alternator is energized it will make a magnetic field and the screwdriver will stick to it. At least we found some answers for another electrical gremlin.

[SmallTires]

Thank you. I do appreciate the help as I am an extreme newbie to these vehicles. I am going to work on all of this pending battery arrival and update at shortly.

[JACook]

By the way, the gauge in the dash for charging is often bad in these cars. My alternator charges at 14.2 and my gauge never moves.

The problem with the Fox Amp gauge is seldom the gauge itself, but rather oxidation in the connectors
that feed the gauge. This style ammeter uses a very small differential voltage to move the needle, and
it doesn't take much oxidation to stop it from moving. I have yet to find one of these I couldn't get working
by cleaning connections and applying dielectric grease, provided the wiring wasn't hacked.

The same style gauge was used on 1st-gen Mustangs, but rather than having both legs crimped into the
harness like on a Fox, the 1st-gen Mustang had one leg on a separate ring lug on the starter relay. I
-have- seen those ammeters go up in a puff of smoke.

[86project]

The problem with the Fox Amp gauge is seldom the gauge itself, but rather oxidation in the connectors
that feed the gauge. This style ammeter uses a very small differential voltage to move the needle, and
it doesn't take much oxidation to stop it from moving. I have yet to find one of these I couldn't get working
by cleaning connections and applying dielectric grease, provided the wiring wasn't hacked.

The same style gauge was used on 1st-gen Mustangs, but rather than having both legs crimped into the
harness like on a Fox, the 1st-gen Mustang had one leg on a separate ring lug on the starter relay. I
-have- seen those ammeters go up in a puff of smoke.

Plus like you said it is a amp gauge not a volt gauge. They do have each type and this is a amp gauge. The needle is designed to not move much. If you have a under or over charge the gauge will show it, otherwise it don't move much.

[grabbergreen84]

The ammeter is a charge gauge. Amperes? It shows whether the system is charging, or discharging. If you turn on all of your lights and accessories with the engine running, it will probably point toward D. Turn off the lights and accessories and leave the engine running, and it should move toward the C. Disconnect all power, and it should center. It worked in my '82, but I never got it working on my '84.
I have heard of ammeters possibly causing fires.

[JACook]

There's a lot of mythology around about Ford ammeters. This is understandable, partly because
people are generally not familiar with how Ford did ammeters, and partly because the newest
Mustangs to come with ammeters are about 27 years old.

The ammeter in a Fox Mustang is actually a very sensitive voltmeter, that measures current flow
by sensing the voltage drop across a length of wire in the harness. This is what's known as a shunt
ammeter. The voltage drop across the shunt is proportional to current flow, and in polarity with
the direction of current flow.

The shunt is in the main power feed from the battery, before the alternator, so it measures net
current flow into and out of the battery. With the engine running, and the battery at full charge,
the gauge will not show much charge or discharge as long as electrical demand does not exceed
what the alternator can supply.

Right after startup, a properly functioning gauge will normally swing about halfway toward "C",
then move back to center after the battery regains enough charge that the alternator steps down.
A properly functioning gauge will also show fluctuations with abrupt load changes, because the
alternator takes a bit of time to react to the demand.

Full swing on a Ford ammeter takes around 50mV, so it doesn't take much oxidation to prevent
one from working. I'm never surprised when guys just assume they never did much.

[Domino]

What part is cleaned and greased on the gauge? The terminals where it goes into the cluster? This is literally one of the last two things to get working on my car and I figured I might as well attempt it today.

[SmallTires]

Well I got the battery back. I replaced the IAC and the TAB and TAD solenoids. It fixed the 23 and 82 codes with key one engine off. Though now I am showing an issue with the neutral safety switch, code 67, which had been jumpered much to my frustration as I replaced just about all the wiring today associated with it. I started the car briefly to see if the idle issue of surging had fixed itself, it did not. It is still surging. I shut it down because I need to find why my alternator is not charging the battery. I didn't have time to right now, and I didn't want to run the battery down again. Battery reads 12.9 volts at the moment. I feel like I am just chasing my tail.

[Domino]

Code 67 will also come up if you scan the car while it is in gear. If you put it in neutral and scan it it should go away. It is actually for the NGS. That is the neutral gear switch it is located on the top of the T5 in the cover that houses the shift forks. Did you check all of your vacuum lines? Especially the ones to the MAP and the canister purge if it is still equipped. Did you check the wiring to the alternator like I suggested?

[JACook]

I don't recall whether your '86 is 5-speed or Automatic, but from some of the preceding, it seems
you have a 5-speed.

The 5-speed Fox Mustangs do not have a neutral -safety- switch. The later SEFI models do have
a Neutral Gear -Sensor- switch, but I'm not sure the '86 had one. The NGS switch is on the top of
the transmission, in the same place as the 5th gear switch that is used on models that have the
upshift light. That switch is supposed to be closed in every shifter position except 5th. I believe
the NGS is closed only in neutral.

The only -safety- switch you should have on a 5-speed Mustang is on the clutch pedal.

What part is cleaned and greased on the gauge? The terminals where it goes into the cluster? This is literally one of the last two things to get working on my car and I figured I might as well attempt it today.

There are basically six connection points that need to be attended to, to get the ammeter working.
Four of those are on the cluster itself, where the harness plug attaches, and where the flex circuit
connects to the gauge. I generally like to give the entire flex circuit a bath in white vinegar, then
a good rinse and dry. The corresponding pins in the connector can be removed and dipped in a
small container of white vinegar, such as a shot glass. The wires are red/orange stripe, and yellow/
light green stripe.

I do the same with the gauge posts and nuts (but don't leave them too long in the vinegar, or the
plating will come off the nuts). To soak the gauge posts, I remove the gauge and stand it up in a
small glass of white vinegar with the posts down. Of course you want to mind that no part of the
gauge itself is immersed.

Once everything is clean and dry, I wipe some dielectric grease on every connection pad on the flex
circuit and connector pins, as well as a bit on all the gauge posts.

The other two connections are a bit harder to get to. They're in one of the harness connectors on
the top of the pork chop brace under the dash. Those I like to remove the pins from the connectors,
and dip them in a shot glass of white vinegar, then rinse and dry. Make sure the pins make tight
contact, and coat with dielectric grease before putting them back in the connectors.

[SmallTires]

The car is a five speed and the code comes up when the vehicle is started in neutral. The vacuum to the MAP is new. I will check the lines to the canister purge. Guess it is time for the old carb cleaner vacuum leak spray down test. I have not checked the wiring for the charging system yet due to time constraints. I should ad the vehicle will still not start without the ignition jumper wire to the starter solenoid. I have all wiring replaced including back up sensor in the trans and still no turn over without the jumper.

[Domino]

Make sure the NGS is plugged in. If the transmission was ever out someone may have not plugged it back in. Vacuum lines on a speed density car can cause you all sorts of grief. The carb cleaner is not a bad idea.