Electrical Issues :( (WITH VIDEO)

Kent535 · January 26th, 2013, 03:15 PM

Maybe you guys could help me diagnose this problem. Spent OVER 5 hours trying to find the issue but no luck. Been driving me crazy so alot of input from alot of different people would be great!
Will be watching this thread and responding for a while.
Any questions feel free to ask to help solve the issue quicker.

87 Mustang electrical problems - YouTube

FastStang91Lx · January 26th, 2013, 03:23 PM

Check your grounds under the dash and don't worry so much about the stock volt gauge anyway. You have the aftermarket one. And make sure your dash frame to chassis bolts are tight also. On second thought, just add a ground from chassis to dash frame. Pull it right from the battery if you want.

Kent535 · January 26th, 2013, 03:30 PM

Originally Posted by FastStang91Lx

Check your grounds under the dash and don't worry so much about the stock volt gauge anyway. You have the aftermarket one. And make sure your dash frame to chassis bolts are tight also. On second thought, just add a ground from chassis to dash frame. Pull it right from the battery if you want.

Well thats the thing. I wouldnt worry about it since my aftermarket one is reading right. but when i have everything on at idle the volts goes down.
Also my lights and turn signals dont work because i left that connected directly to the efi wiring harness and when the stock gauge voltage drops the lights turn signals and radio shut off :/

FastStang91Lx · January 26th, 2013, 07:25 PM

Like I said, it's probably a ground issue since the aftermarket gauge isn't dropping. That would signal an alternator problem. The grounds for the instrument panel, radio, etc. are are on the underside of the dash on the dash frame. Also make sure your battery to chassis ground is good also. You're gonna have to get under there and get your hands dirty. No one can tell you the exact spot to look to fix your problem. It could be a number of things. Grounds first, then go from there.

deltahector89 · January 27th, 2013, 11:28 AM

Is that alternator from a carbed car? They put out alot less juice then an alternator from an efi car. Almost looks to me like your alternator isnt sufficent enough to run the massive amount of electronics you got in that thing. Just saying if that 351 swap is using a carbd alternator thats possibly only putting out 60 amps then thats your problem

dbshea · January 27th, 2013, 12:14 PM

While I have nothing new tech wise to say (I think these guys covered my opinion well) I must say, that's the best "help" thread I've seen! The video was smart man.

Kent535 · January 27th, 2013, 01:22 PM

Originally Posted by deltahector89

Is that alternator from a carbed car? They put out alot less juice then an alternator from an efi car. Almost looks to me like your alternator isnt sufficent enough to run the massive amount of electronics you got in that thing. Just saying if that 351 swap is using a carbd alternator thats possibly only putting out 60 amps then thats your problem

The alternator is a 70 Amp replacement. My electric fans pull 30 amps alone.
I am curious and probably guessing this is the issue however it seems to be fine at idle. Does anyone know how many amps an aftermarket Double spark ignition box consumes?

Stang6er · January 27th, 2013, 03:37 PM

I have a msd 6a box that pulls 1 amp per 1000 rpm. Idk bout other boxes

deltahector89 · January 27th, 2013, 10:15 PM

Seems like the accessories ran off of the fuse box are taking the hit while the accessories ran off the battery are ok, what is the voltage at the post on the back of the alternator? Then check voltage at the end of the lead from the alternator to see if their is a parasitic loss in the charging cable. Then check the voltage at the fuse box.. Where did you tap into for your aftermarket voltage gauge? It doesn't dip does it?

Kent535 · January 27th, 2013, 11:23 PM

Originally Posted by deltahector89

Seems like the accessories ran off of the fuse box are taking the hit while the accessories ran off the battery are ok, what is the voltage at the post on the back of the alternator? Then check voltage at the end of the lead from the alternator to see if their is a parasitic loss in the charging cable. Then check the voltage at the fuse box.. Where did you tap into for your aftermarket voltage gauge? It doesn't dip does it?

I will check the voltage when i get my fuel cell in the trunk(Tuesday afternoon) Waiting on some fittings. As far as the accesories EVERYTHING including (fuel pump,fans, ignition box, coil, and all of the gauges are running directly off the battery via the switch panel. The radio is ALSO connected direct to the radio via a toggle switch. What gets to me is that even tho the radio is connected direct it is acting up with voltage issues(Cutting in and off)

deltahector89 · January 28th, 2013, 09:22 AM

So the yellow and red wire from the radio are direct? Ran your own ground too then? Just making sure your not using anything from the factory harness

Kent535 · January 28th, 2013, 04:42 PM

Originally Posted by deltahector89

So the yellow and red wire from the radio are direct? Ran your own ground too then? Just making sure your not using anything from the factory harness

Well the red wire is
Dont know about the yellow one

deltahector89 · January 28th, 2013, 09:35 PM

Red wire is only for memory, ie clock presets etc. yellow is the actual power wire and if that's ran into the factory harness then that to is ran to the fuse box

deltahector89 · January 28th, 2013, 09:39 PM

just remember under powering electronics is just as bad as overpowering them. Underpowering creates heat. heat is the most common cause of electronic failure

January 26th, 2013, 03:23 PM	#2
FastStang91Lx I Post Entirely Way Too Much 1991 Mustang LX 5.0 Join Date: Jan 2010 Location: Minnesota Posts: 7,001 iTrader: 2 reviews	Check your grounds under the dash and don't worry so much about the stock volt gauge anyway. You have the aftermarket one. And make sure your dash frame to chassis bolts are tight also. On second thought, just add a ground from chassis to dash frame. Pull it right from the battery if you want. __________________ FastStang's Ongoing projects thread Click here!

January 26th, 2013, 07:25 PM	#4
FastStang91Lx I Post Entirely Way Too Much 1991 Mustang LX 5.0 Join Date: Jan 2010 Location: Minnesota Posts: 7,001 iTrader: 2 reviews	Like I said, it's probably a ground issue since the aftermarket gauge isn't dropping. That would signal an alternator problem. The grounds for the instrument panel, radio, etc. are are on the underside of the dash on the dash frame. Also make sure your battery to chassis ground is good also. You're gonna have to get under there and get your hands dirty. No one can tell you the exact spot to look to fix your problem. It could be a number of things. Grounds first, then go from there. __________________ FastStang's Ongoing projects thread Click here!

January 27th, 2013, 11:28 AM	#5
deltahector89 Regular Join Date: Sep 2012 Location: Michigan Posts: 124 iTrader: 0 reviews	Is that alternator from a carbed car? They put out alot less juice then an alternator from an efi car. Almost looks to me like your alternator isnt sufficent enough to run the massive amount of electronics you got in that thing. Just saying if that 351 swap is using a carbd alternator thats possibly only putting out 60 amps then thats your problem

January 27th, 2013, 12:14 PM	#6
dbshea In over my head 1990 GT Slow? Join Date: Aug 2010 Location: Oceanside, Ca Posts: 565 iTrader: 0 reviews	While I have nothing new tech wise to say (I think these guys covered my opinion well) I must say, that's the best "help" thread I've seen! The video was smart man.

January 27th, 2013, 03:37 PM	#8
Stang6er Regular 87 mustang gt Join Date: Jan 2010 Posts: 195 iTrader: 0 reviews	I have a msd 6a box that pulls 1 amp per 1000 rpm. Idk bout other boxes

January 27th, 2013, 10:15 PM	#9
deltahector89 Regular Join Date: Sep 2012 Location: Michigan Posts: 124 iTrader: 0 reviews	Seems like the accessories ran off of the fuse box are taking the hit while the accessories ran off the battery are ok, what is the voltage at the post on the back of the alternator? Then check voltage at the end of the lead from the alternator to see if their is a parasitic loss in the charging cable. Then check the voltage at the fuse box.. Where did you tap into for your aftermarket voltage gauge? It doesn't dip does it?

January 28th, 2013, 09:22 AM	#11
deltahector89 Regular Join Date: Sep 2012 Location: Michigan Posts: 124 iTrader: 0 reviews	So the yellow and red wire from the radio are direct? Ran your own ground too then? Just making sure your not using anything from the factory harness

January 28th, 2013, 09:35 PM	#13
deltahector89 Regular Join Date: Sep 2012 Location: Michigan Posts: 124 iTrader: 0 reviews	Red wire is only for memory, ie clock presets etc. yellow is the actual power wire and if that's ran into the factory harness then that to is ran to the fuse box

January 28th, 2013, 09:39 PM	#14
deltahector89 Regular Join Date: Sep 2012 Location: Michigan Posts: 124 iTrader: 0 reviews	just remember under powering electronics is just as bad as overpowering them. Underpowering creates heat. heat is the most common cause of electronic failure

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