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Dash Gauges Acting Up

 
cushman350
Enthusiast
Posts: 635
Joined: 07/06
Posted: 08/13/13 01:01 PM

First, I've owned this car since 1969, I know it's history. It left the Ford factory as a 1965 5R09K and titled a 1966 GT 350.I have added an Old Air A/C system with electric fan/shroud that requires a 40 amp fuse to run cooling fan. I also have a complete MSD 6AL and MSD distributor ignition system that uses more power than I was aware. I added at the time, a 75 amp ho alt, which unknown to me at the time, was inadequate, but no dash gauge issues. An online supplier of high output alternators had a form to figure my needs and came out I need at least 90 amps. Two weeks ago, I installed a 100 amp alt. with the same wiring as original( not a one-wire ). It showed to be putting out 17.6 volts, headlights very bright. So, I replaced the stock type volt. reg( with wound coils and springs and points)with a solid state update and the voltage output dropped to 14.6, ok, right?

Since then, while cruising, the dash gauges intermittently don't work. When I notice they are off, I shut off the motor and restart and 9 times out of 10, it will get them working again. Does the small voltage regulator on the back of the instrument panel control all or just some of the gauges? Is this my grelim or am I still searching?

I say this because when the dash gauges loose power, so does the blower motor on the Old Air self contained A/C system that blows inside the car. But, the radiator fan is not effected, it has its own power source and relay.

What say Wayne? or any knowledgeable auto electric aces.  

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waynep712222
User
Posts: 223
Joined: 04/13
Posted: 08/13/13 05:49 PM

oh my... everybody knows my name... guess i might have to get a new one..

first start with the voltage drop test..

engine running head lights on.. digital volt meter set to 20 volts DC..

1.   negative battery post to the positive battery post..  14.1 to 14.6 is expected

2.   Negative battery post to the engine block.. 0.04 volts is expected

3.   Negative battery post to the body...  0.02 volts is expected..

4.   Engine block to body. usually at the firewall..  0.02 volts is expected.

post results..

1..

2..

3..

4..

..

now.. on the charging system

which voltage regulator wiring do you have...

is it set up with 3 wires..   F S A

or is it set up with 4 wires..  F S A I



with the 100 amp alternator conversion.. please install an additional output wire to the starter solenoid ... so you reduce the load on the factory wiring... you can let the smoke out of the fusible links with that kind of amperage..


Fordchargelitealtdrawing  

Post Reply
70bird
User
Posts: 86
Joined: 07/13
Posted: 08/13/13 06:11 PM

well, it's obviously losing power which means bad alt or regulator, try a new high quality regulator

if it still does it try an old alt, if it works fine your alt is likely bad.  

Post Reply
waynep712222
User
Posts: 223
Joined: 04/13
Posted: 08/13/13 06:18 PM

as for the cluster..

take a set of jumper cables...

toss them on the ground under the car..  one end near the drivers door..  make sure they don't touch...  just hook up the NEGATIVE one at the Negative battery post first..

walk around to the drivers door...   hook your digital volt meter to the negative cable..  reach in start the engine.. turn on the headlights..   start probing things you can easily get to...

each fuse in the fuse block... all except the short fuse may have full battery voltage on them..  depending if the circuit is on or not.. i am taking you have a wiring diagram set for this car...

see if you can probe the cigar lighter  hot terminal...

do you get close to full battery voltage..

turn on the defroster fan.. see what the voltage is on the cigar lighter again..

post results..

do the same test.  but with only the positive jumper cable hooked up...  and write down what you tested on the negative..

you should get much smaller voltages.. less than 0.1 volts.. i would imagine 0.06..

if you have the time.. i would like you to test the various outputs of the ignition switch... but this takes more brain power and time than i have right now..

i will work on this after you post some numbers..  

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waynep712222
User
Posts: 223
Joined: 04/13
Posted: 08/13/13 06:22 PM

on the dash board...

grounds are important..

there should be a ground wire from the back of the engine block to the firewall..

inside the dash.. there should be a ground wire from the firewall or brace to the back of the cluster...

66 Mustang Cluster Ground Location  

Post Reply
MustangMan
Moderator
Posts: 259
Joined: 08/11
Posted: 08/14/13 07:34 AM

My first question...

Where is the A/C blower wiring connected? If that circuit is losing power as well we can narrow down that and the gauge power issue to possibly be the same circuit or multiple circuits...

Mark
.  
Mark Houlahan
Brand Manager
Mustang Monthly Magazine

1965 FFR Roadster 427W/TKO-600 5-speed
1966 Mustang 289-4V/C4 Auto
1968 Mustang 4.6L Three-Valve/5R55S Auto
1990 Mustang 306/AOD
2002 Explorer Sport Trac 4.0L V-6/5R55 Auto
2005 F-150 4x2 4.2L V-6/4R70W Auto

Post Reply
cushman350
Enthusiast
Posts: 635
Joined: 07/06
Posted: 08/14/13 11:37 AM

Icon QuoteMustangMan:
My first question...

Where is the A/C blower wiring connected? If that circuit is losing power as well we can narrow down that and the gauge power issue to possibly be the same circuit or multiple circuits...

Mark
.


This may take a while, I'll have to be hand led through the electric tests. But Mustang Man, yes, that part of the issues about the blower fan being effect raised a flag to me also. Strange just the dash gauges and a/c fan only are effected. The A/C vent covers the fuse block and has to be removed, but I suspicion the fans power source may have helpful. I think I may have wedged the wire between a fuse end and its clip. I'm just gathering ideas before jumping into those small spaces. It's about 100°F daily in my garage this time of year.

All ground straps are in place, I recently rebuilt my 347 and retrofit a roller cam and lifters myself, so I know the ground to firewall is clean and tight.

By the way, the difference between the flat hyd lifter cam and a similar roller cam is like a GED and a sheep skin from Harvard. The personality of the hp from the same engine is amazing. The engine actually runs cooler. It now handles the horrid summers here getting to 108°. I used to have to shut off the A/C to keep from overheating but now the same cooling system can maintain stop and go driving in town. That convinced me.  

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waynep712222
User
Posts: 223
Joined: 04/13
Posted: 08/14/13 01:34 PM

the voltage drop test with the digital volt meter can be done in under 2 minutes..

or..

start taking things apart and cleaning them..

start with the battery cables to the starter relay..  count the wires on the battery cable side... take it apart and clean the ring terminals and the stud with a 4 buck stainless steel wire tooth brush..

Mustang Starting System5

65 66 Mustang Ground Cables

how does the engine harness plug in to the dash harness.. is it one piece.. using multiple bullet connectors..  have you unplugged it and checked it for loose terminals.. or burned terminals..

how old is the ignition switch.. can you disconnect the battery and remove the ignition switch to check the wiring...

as for the HOT ROOF in the shop.. i have several fixes..

rain bird on a tall pipe with a TEE at the bottom with a female hose connector and a cap on the bottom...  soaker hose on the end of a conventional hose and tossed up and worked back and forth across the peak of the roof with a LONG pole from the ground... turn the water on. the soaker or rain bird wet the roof and take the heat out of it in just a few minutes..  there are sprinklers that have a curved bar with 2 dozen holes in it.. they rock back and forth.. one of those set out from the wall .. can also cool the sun facing walls..  it only takes a minute or two of water flow to take the heat out of the roofing or out of the walls..  

Post Reply
70bird
User
Posts: 86
Joined: 07/13
Posted: 08/15/13 12:21 AM

The factory ac was connected to the accesory fuse i believe.

does the problem occur with the ac off.  

Post Reply
cushman350
Enthusiast
Posts: 635
Joined: 07/06
Posted: 08/16/13 07:15 AM

Icon Quote70bird:
The factory ac was connected to the accesory fuse i believe.

does the problem occur with the ac off.




No it does not as I found out yesterday. I drove it without a/c and the gauges operated fine. When I got back to the house I switched ON the a/c and the gauges immediately dropped out. After a short time, sitting, all function returned.
This after market a/c has worked in this car since 2007 with no issues until now. This gauge/blower issue didn't begin until the new high output alternator and a new solid state voltage regulator was installed. This new 100 amp alt. has upset the balance methinks. Thanks for the ammo.

Going to add Neg to body ground and add a heavier gauge alt. to battery side of the solenoid. Then make sure a/c blower power supply is connected to Acc or Ign On properly fused.

Then, if issues remain, we get knee deep electrical tests.

The regulator is a 4 blade and would have 65 GT wiring because it is really a 1965 Mustang, early carryover 1966. The amp gauge is the inductive loop type, no connections plugged in or held with nuts or washers.  

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waynep712222
User
Posts: 223
Joined: 04/13
Posted: 08/16/13 07:55 AM

both the instrument cluster voltage regulator and the power for the blower and AC compressor in 65's come off the threaded stud on the center of the back of the ignition switch..

so.. you will need to monitor the voltage there...

do you have a circuit tester?? test light..
HF 30779 Zpsc0772e7e

put the clip end on the threaded stud on the back of the ignition switch..

stick the probe into something to ground it..

start the turn the key on.. does the light come on???

start the engine... is the light still on...

turn on the AC blower... is the light still on and just slightly dimmer than it was before?? or did it go dark...

you could have a bad connection on the positive side.. between the battery positive and ignition switch...

you could have a bad connection on the back of the ignition switch...

you could have a bad ignition switch..

one step at a time...

we are trying to narrow down where the partial connection is...  

Post Reply
cushman350
Enthusiast
Posts: 635
Joined: 07/06
Posted: 08/16/13 09:58 AM

UPDATE:

Throw out all previous notions that this gauge power drop is only with a/c being activated. This morning I drove the Mustang without switching on the a/c and the dash gauges all lost function about 5 minutes from leaving home. Never restored. And now the blinkers have stopped, no flash, no nothing. Got home and found only 12 battery volts, nothing be produced at the Batt post on the back of the alternator (quality part, 6 hours on it). Not the 14.6 of yesterday. Back to square one with the charging system, just running on the battery now. Got to get serious.

The ignition switch is old, replaced in early 70's. Anything that gets power through the accessory circuit from the ign sw. is now dead like radio. New ignition switch is next.

Also, the volt. reg. has 4 blades and the factory plug has 4 receptacles but only 3 female plugs and one empty hole without any metal plug. Always been this way, normal? And the plug seems to fit loosely on the new regulator, it didn't on the old oem type reg. Female end will be tweaked to tighten.

Got to get to Harbor Freight for digital test meter and test light, all I have is the old one with a needle.  

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waynep712222
User
Posts: 223
Joined: 04/13
Posted: 08/16/13 06:56 PM

harbor freight #37772 is a decent and inexpensive meter at 20 bucks..

if you have any points type cars.. they have
LCD Automotive Multimeter with Tachometer Kit Item #95670 for 40 bucks..
this one reads dwell.. so you can adjust your points.. instead of the 20 buck digital volt meter..

a few of the $0.49 Steel Detail Brush Item #40442 to help clean electrical ring terminals..


3 wires out of 4 connectors is actually normal for cars with AMP meters... as there is no alternator lamp to start the regulator..

please count the wires on the starter solenoid and take them off and start wire brushing the ring terminals.. then the stud and nut faces.. then reassemble..

do you know how to get the ignition switch out.. turn key to accessory position.. push paper clip slightly into the hole.. turn left slightly more..  pull lock out of face of dash... please.. DO NOT ROTATE KEY IN LOCK while its out ... you won't like what happens..  you can reach behind the dash.. holding the chrome bezel  push the switch forward and twist slightly. it comes apart like taking out a tail light bulb.. its spring loaded..

this will allow you to drop the ignition switch.. to unbolt the wires from the stud.. and wire brush the ring terminals.. and install the new ignition switch..

the whole problem could still be corrosion on the back of the ignition switch stud..

but cleaning only wastes time.. costs almost nothing. cures a lot of evils..

as a matter of fact.. the 66 fairlane is sitting nearby.. perhaps i will snap some pictures of it.. when it gets back in line for service soon..  

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cushman350
Enthusiast
Posts: 635
Joined: 07/06
Posted: 08/21/13 09:51 AM

I'm gathering parts for the replacing of ign sw, inst panel volt reg and fresh alternator and cleaning of all grounds. Adding an 8 or 10 gauge wire from alternator to Batt side of solenoid. Then, I want to perform all the tests that wayne has asked for.

I have no points, its got a MSD 6AL ign. control and Pro billet MSD electronic dist.

Even the weather has cooled down to just 94° during the afternoon.  

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waynep712222
User
Posts: 223
Joined: 04/13
Posted: 08/21/13 05:33 PM

pick up one of these from almost any parts store..

or a pair of them...

back of the heads to the firewall...

Ground Strap 15 Inch Zpsbc9293c1



with an MSD external box ignition..  you may want to also ground the big black wire of the MSD BOX to the Engine block  or where you attach the ground straps above..

why.. when the spark is created in the MSD box. yep starts there the high voltage generated by the coil has to make a complete circuit thru the ignition system .. then into the heads after it jumps the gap.. but how does it get back to the msd box.. where did you ground it.. installation says to hook it to the battery terminals..   shorten the path.. go directly to the engine block..

racers have actually taken braided ground straps and connected both heads the distributor housing and the main ground for the MSD unit and gotten a much better spark and a LOT less failures..

MSD runs several hundred volts to the positive primary side of the coil... and controls the negative side directly inside the module.. this saturates the coil faster so additional sparks can be created..

long ground runs increase the time and resistance thru the circuits.. do you really want the high voltage negative spark going the LONG way around .. up the negative battery cable to the battery terminal to get to the MDS wiring..  or from the heads.. directly to the msd wiring...

yep.. a little more complicated.. but i bet your MDS module LASTS a lot longer ...  

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