Classic Mustangs List Archive

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Mail From: jerry bryant (email redacted)

I have seen this question asked here several times, but I have never read a
answer to the question. When switching from dummy lights to a gauge/tach
setup on a 71-73 Mustang what needs to be switched? Last summer I bought
the under dash and engine compartment wiring harness, along with the tach
and gauge cluster. After fighting several problems I finally got it
installed. However, I could never get the car to start. It would turnover,
and catch for a split second then just totally die. I had spark and fuel.
I have heard that when doing this switch, that the alternator wiring harness
must be changed ( I did not do this.) If so, why? Also, I have a 71 and
the wiring harness was from a 73, the only difference I saw was the number
of wires going to the regulator was more than on my 71. Does this matter?
I really would like to get my car running again, it has been sitting for
close to two years. PLEASE SOMEONE HELP. Any help would be GREATLY
appreciated and accepted with open arms.

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Mail From: speegle (email redacted)

jerry bryant wrote:
>
> I have seen this question asked here several times, but I have never read a
> answer to the question. When switching from dummy lights to a gauge/tach
> setup on a 71-73 Mustang what needs to be switched? Last summer I bought
> the under dash and engine compartment wiring harness, along with the tach
> and gauge cluster. After fighting several problems I finally got it
> installed. However, I could never get the car to start. It would turnover,
> and catch for a split second then just totally die. I had spark and fuel.

Don't know the particulars about the swap but do you have power to the
coil when the key is on and the starter is NOT turning? (I would guess
not) if so you have a primary wire that is disconnected at some point.

Was the car you got the wiring from a clock or tach equipped car?

Did you swap the guage cluster and add the guages? if not I'ld guess the
primary wire is not connected near the switch.

Jeff Speegle
MCA ANHJ

This read-only message was archived from a public mail list.
Mail From: jerry bryant (email redacted)

>Date: Fri, 21 Feb 1997 19:36:06 -0800
>From: speegle <(email redacted)>
>To: (email redacted)
>Subject: Re: Dummy lights to gauges
>Message-ID: <(email redacted)>
>
>jerry bryant wrote:
>>
>> I have seen this question asked here several times, but I have never read a
>> answer to the question. When switching from dummy lights to a gauge/tach
>> setup on a 71-73 Mustang what needs to be switched? Last summer I bought
>> the under dash and engine compartment wiring harness, along with the tach
>> and gauge cluster. After fighting several problems I finally got it
>> installed. However, I could never get the car to start. It would turnover,
>> and catch for a split second then just totally die. I had spark and fuel.
>
>Don't know the particulars about the swap but do you have power to the
>coil when the key is on and the starter is NOT turning? (I would guess
>not) if so you have a primary wire that is disconnected at some point.
>
>Was the car you got the wiring from a clock or tach equipped car?
>
>Did you swap the guage cluster and add the guages? if not I'ld guess the
>primary wire is not connected near the switch.
>
>Jeff Speegle
>MCA ANHJ


Thanks for the help!! I do have power to the coil when the key is on. The
car does have spark and fuel, but after it catches it dies within a second.
I am thinking that it has to do with the alternator wiring being different
between the gauges and dummy lights, but I am not sure.

The wiring harness I bought has the tach. I did also add the tripod gauge
cluster. I am not sure what you are asking/telling me here, "Did you swap
the guage cluster and add the guages? if not I'ld guess the primary wire is
not connected near the switch." What switch are you talking about? Thanks
again for your help.

This read-only message was archived from a public mail list.
Mail From: speegle (email redacted)

jerry bryant wrote:

> Thanks for the help!! I do have power to the coil when the key is on. The
> car does have spark and fuel, but after it catches it dies within a second.
> I am thinking that it has to do with the alternator wiring being different
> between the gauges and dummy lights, but I am not sure.
>

Not a electrical expert but from my understanding there are two systems
at work when we start out cars. Thought thew starter switch we get
direct currect through the soleniod to the coil. Once the starter is
turned (or let go) from start to run the secondary power from the
battery through the starter switch, resistor wire to the coil takes
over. It is common to see someone with a bad Ford tach, removed tach or
rally pak, getting the car to start but it dies ones the starter is
disengaged. That's why I asked about the transfer of guages since I
could see that someone might add the ceneter guages and the wiring
without changing the main guage cluster. And in the process leaving the
the secondary loop open.


> The wiring harness I bought has the tach. I did also add the tripod gauge
> cluster. I am not sure what you are asking/telling me here, "Did you swap
> the guage cluster and add the guages? if not I'ld guess the primary wire is
> not connected near the switch." What switch are you talking about? Thanks
> again for your help.

But if you have power to the coil with just the key on. If you have
power to the coil while the starter is engaged, and after starting the
car dies and you still have power to the coil then I would start looking
elsewhere (non-electrical) for the problem.

Anyone else want to jump in here?/

Jeff Speegle
MCA ANHJ

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Mail From: (email redacted) (email redacted)

jerry bryant wrote:
>
> When switching from dummy lights to a gauge/tach setup on a 71-73 Mustang what needs >to be switched?


Jerry:

A couple of months ago, I also bought the under dash, engine wiring and
gauges (tach and center) from a 1973 Mach I which eventually I would
like to install in my 1972 convertible. I noticed that the original
headlight harness on my car ends with only four wires, while the 1973
Mach I wiring ends with six wires. I asked the group
why but did not get a response.

I believe that you must purchase the correct alternator harness before
the tach will work (I have seen them for sale for about $50 in the
California Mustang catalog), but I do not know for sure. For 1973's
there are two different harnesses for cars with gauges (lo amp and 70
amp). If you have not already done so, the oil and water sending units
must be changed.

As to why your car does not start: could it be something not related to
the new wiring?
Did it start OK before you switched the wiring? Does everything else
seem to work OK such as the headlights, interior lights, etc. Do you
know if the 1973 donor center gauge and tach/speedometer clusters worked
before you bought them? If the instrument cluster is shorted out, it
could be causing your starting problem.

Please let me know what other problems that you had installing the new
harnesses. I am
still considering doing the same.

Frank

1972 convertible
1992 GMC Typhoon
1975 Kawasaki Z-1

This read-only message was archived from a public mail list.
Mail From: (email redacted) (email redacted)

(email redacted) wrote:

No he didn't. My real e-mail address is (email redacted). I had some
Netscape
problems recently and accidentally changed my e-mail address name to
(email redacted) which is non-existant. Sorry about that.

> jerry bryant wrote:
> >
> > When switching from dummy lights to a gauge/tach setup on a 71-73 Mustang what needs >to be switched?
>
> Jerry:
>
> A couple of months ago, I also bought the under dash, engine wiring and ..........

Frank
1972 convertible