The usual Ford electrical stuff.........

Well, the usual frying of the main wire to the alternator on the '85. This time it got the whole wire all the way through the fusible link. I ran all new wiring from alt. to regulator and soldered in a new link. Installed a new alt. & reg. Charged the battery and fired it up. It's discharging, especially under load. Funny thing is, when running, I get 14.4 volts with a VOM, but it shows a discharge on amp meter. I used an amp meter on the wire from the alt. & it shows -40 amps. Checked amperage at +batt. cable & get a +25A. Took the alt. back & they said it's ok. Now I'm thinking it's putting out volts but no amps. I can full-field the alt. & it puts out 18V but still shows a discharge on amp gauge. WTF?????!!!!
Any ideas? I'm about fresh out.

------------------
Dave
'83TC
'85TC
'87TC

Measure batt voltage at 2000 RPM with all accessories off... should be in low 14 V range. Now, turn on the headlights, and blower motor on high. Voltage shouldnt drop by more than avout 1/2 Volt. If these tests pass, the alt is charging the batt properly, and supplying enough amps to the electrical system.

Are you sure you put the new wire from the alt to the correct side of the (probably yellow and about 4" long) amp gauge shunt wire? If wired to the wrong side of the shunt wire, the amp gauge will act screwy.

------------------
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)

Originally posted by Jeff K:


Are you sure you put the new wire from the alt to the correct side of the (probably yellow and about 4" long) amp gauge shunt wire? If wired to the wrong side of the shunt wire, the amp gauge will act screwy.

[/B]

Hey Jeff, Does this yellow wire come straight off the starter solenoid to a weld splice that joins it to 2 other wires? I think they're Blk/Or. The link that burned up was the one that comes off the yellow wire. Ok, this might be where the problem is. What I did was cut the damaged link and wiring out. The short yellow one was not damaged but I just left it where it was and put in new wiring from the alt. reg. to fusible link wire and then I put about a 4" piece of wire (Yep, yellow) from the link to the starter solenoid. So this yellow wire coming from the solenoid is the shunt?And it's special enough it needs to be back in the circuit? If this is the case, it ends about a 20 yr. search for the infamous Ford shunt. I had a '70 Ford van and I never could get the gauge to work. The books would always mention the shunt but never the location. I did check things out again earlier today. It's putting out volts & amps like it should so I guess we're down to just the gauge.


------------------
Dave
'83TC
'85TC
'87TC

[This message has been edited by TRBOBRDS (edited 07-14-2002).]

The amp meter is actually a low voltage voltmeter that is connected across the yellow shunt wire. Current thru the shunt wire produces a voltage drop across the wire that the amp meter measures... ohms law, V=iR. Not real familiar with the wiring on the 85, but probably should go something like this: Alt output wire to splice at one end of yellow shunt. Probably several wires at this end. Other end of shunt goes to big splice with a bunch of wires, one of which goes to the batt term. of the starter solenoid. Power for most of the cars electrical system comes from that big splice at the alternator end of the yellow shunt wire. The wire to the batt terminal of the solenoid is only for charging the batt.

------------------
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)

[This message has been edited by Jeff K (edited 07-15-2002).]