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cudacarl
01-05-2013, 02:53 PM
I'm suspecting a intermittent problem with my starter relay. right now i have the sol wire to the starter disconnected from the relay so it wont turn over and kill my battery. the question is when i go fron run to start at the ignition switch, should i get 12v positive on the I terminal at the starter relay ?

John Kunkel
01-05-2013, 03:54 PM
Yes, you should get battery voltage at the "I" terminal in the Start position.

cudacarl
01-05-2013, 04:03 PM
ok the voltage is fed from the yellow wire coming from the ignition switch. on the terminal with out the wire connected it should be 0v. here is the problem i've been chasing forever. every once in a while the engine cranks but no ignition. i go from run to off and the engine bumps. then it will start like normal. i replaced the ignition switch in the column and it didn't fix it. here is what i'm getting now. with the sol wire disconnected to the starter and my volt meter on the coil i'm getting 4 volts in run and 6 volts in start. does this sound right ? i wonder if i'm dealing with a votage drop or bad connection somewhere.

440roadrunner
01-05-2013, 04:52 PM
Sounds to me like you somehow have it wired wrong. Has the wiring been modified/ chopped up? What model/ year are we dealing with?

It is important to understand how Mopar ignition/ starting works

Just about all Mopars from the early 60s work the same way. There is actually SEVERAL separate and distinct switches inside the "can" that is the ignition switch

1---accessory, hot in "run" or "accessory"

2--IGN1, or "ignition run" dark blue for many years, hot ONLY in run and NOT hot in "start"

3--Start, yellow for many years, goes only one place--from the switch, through the bulkhead, to one of the two push on terminals of the starter relay. Hot ONLY in "start."

4--IGN2, or "bypass" brown for many years Hot ONLY in start, this goes to the coil+ side of the ballast resistor, and is the ONLY source of ignition power during "crank." It also is a simple circuit, goes directly from the switch, through the bulkhead, and to the coil side of the ballast.

NOTE THAT IGN2 and "start", brown and yellow, ARE NOT electrically connected in any way.

Now, the relay on older cars, up through 69, only had three terminals if a stick, and 4 terminals (one additional "push on" terminal if an auto.

Stick cars 70/ later equipped with a clutch safety switch used the same 4 terminal relay as the auto cars.

So I guess you know by now that the one push on terminal is the coil of the relay, and if no other "push on", then the coil is grounded to the case, so that type relay must be grounded.

A 4 terminal relay (two push on terminals) has an isolated coil, the second push on terminal is routed to the neutral safety or clutch safety, which grounds that terminal.

The big battery stud acts as a handy junction, and is one contact of the relay

The "square" terminal goes to the solenoid and is the the other contact of the relay.

To end this blather, the yellow "start" wire should have NO power at any time except when the IGN switch is twisted to start. ONE THING I would do, is double check this with a light instead of a meter, or else check it with the relay "in operation" IE disconnect the solenoid wire and then leave everything else hooked up when you check for voltage at the start wire.

The reason for this is "electrical leakage." A modern multimeter does not need much current to indicate, and it is possible (We aren't there, LOL) for some odd moisture/ dirt/ corrosion/ etc situation to cause some sort of electrical leakge which is throwing off your logic.

To see this in action, pick one of your cars with a "dirty battery." Probe the battery positive post, and stick the remaining probe around various points right on the battery case. The dirt/ moisture on the case will give you some meter reading.

cudacarl
01-05-2013, 05:03 PM
it's a '73 cuda 340 stock wiring and ignition. this problem started a long time ago (maybe 7 years) and it would never do it at home for me to trace. back around 1989 i replaced the engine harness with a year one harness. other than that there is no rewiring or cutting.
my main question is,

with out the sol connected to the relay to prevent the starter from engaging,

what should the voltage be in

1. run ?
2. start ?

John Kunkel
01-06-2013, 04:42 PM
here is the problem i've been chasing forever. every once in a while the engine cranks but no ignition. i go from run to off and the engine bumps. then it will start like normal.

This problem can often be caused by corroded connections at the firewall bulkhead disconnect. Trace the brown wire at the ballast resistor to the firewall disconnect, remove the connector and manually clean both the male and female spade terminals.

440roadrunner
01-06-2013, 04:51 PM
it's a '73 cuda 340 stock wiring and ignition. this problem started a long time ago (maybe 7 years) and it would never do it at home for me to trace. back around 1989 i replaced the engine harness with a year one harness. other than that there is no rewiring or cutting.
my main question is,

with out the sol connected to the relay to prevent the starter from engaging,

what should the voltage be in

1. run ?
2. start ?

John Kunkel is absolutely correct, the first thing I'd look at is the bulkhead connector.

You did not answer or maybe I did not make it clear---you have a 3 or 4 terminal relay, that is, do you have an automatic, a stick with clutch safety, or a stick with no clutch safety?

1--run--At the yellow wire coming to the relay should read ZERO volts

2-- start-- At the tellow wire should read "same as battery"

cudacarl
01-07-2013, 01:22 PM
4 speed the stater relay has (Batt/Sol/I/G) . the run & start voltage i was looking for was at the coil. i think it's a bad connection too. this is a intermittent problem i've had for years. i can clean everything up and think it's fixed, then six months later it'll do it again. the reason i need the voltage at the coil is, it seems like i have just enough to start it but if i have any drop at all i loose the spark. so what i want to do is start cleaning things up one at a time till i get the correct voltage. i just don't know what that voltage should be. i don't have access to another car to try it on. i need the voltage at the coil with the starter wire disconnected at the starter relay so i don't keep cranking the engine. i need it in run & start.
-thanks

John Kunkel
01-07-2013, 06:14 PM
The RUN voltage at the coil isn't set in concrete because the ballast resistor, by nature, varies the resistance with temperature...however, the START voltage at the coil should always be the same as battery voltage.

440roadrunner
01-07-2013, 08:44 PM
You don't have the coil+ and the start relay interconnected, do you? These are two distinct circuits and switch contacts

cudacarl
01-07-2013, 10:36 PM
i don't know what you mean by having the circuits interconnected. it's a reproduction unmodified harness thats been on the car for over 20 years. in testing the start voltage at the coil, i was getting 9v. if i tested from the coil + to battery -, i would get 12v. if i disconnect either connector on the ballast resistor i get 12v between coil +/-. i'm really just trying to fix the start circuit and get the volltage up. i have a complete wiring diagram. this weekend i might take the harness out and clean & check all connections. if i should have 12v at the coil in start then i know what i'm hunting for.
thanks

chirorod
01-08-2013, 07:40 AM
Should be about 12v at the coil in start. That is intended to give a little more zap when starting. Way back when they started using 12v systems and found that 12v was too much for the points and possibly the coil. So they put in a resistor to cut the voltage to about 9v at the coil, etc. It's amazing how fast 12v would eat up points. But starting wasn't as good, so they put in a separate start circuit that bypassed the resistor. On mopars, the resistor is called a ballast resistor. It has 2 circuits, with a low resistance resistor for start and a higher resistance resistor for run.

440roadrunner
01-08-2013, 12:24 PM
RE--read what I posted CAREFULLY and take EACH circuit one at a time

You have THREE distinct circuits from the IGN switch. That is, inside that "can" that is the switch, there are SEPARATE switches.

1--START RELAY is hot ONLY in "start" traditionally yellow and ONLY goes from the switch, through the bulkhead, to the starter relay. This should be same voltage as battery ONLY in start, should be ZERO in any other position

2--RESISTOR BYPASS or IGN2. Traditionally brown, it works exactly like 1, above, except that it goes ONLY to the coil+ side of the ballast. Should be same as battery in start, and should drop down lower in RUN due to ballast resisto.

3 IGNITION RUN or IGN1. Traditionally blue, it is hot ONLY in "Run" no other key position. This comes from the switch, and powers some of the cluster. It branches off, goes through the bulkhead and becomes the "switched ignition," or "ignition run" buss

Depending on the year of the car it powers.........................

The switch side of the ballast resistor

The blue wire to the alternator field

The IGN feed to the regulator

electric choke if used

carb idle solenoid or distributor retard if used.

It is IMPORTANT to realize that NONE of these 3 circuits are fuse protected.

HOW TO TEST each one.

1----START. Hook your meter from the start wire at the start relay to ground. You want a "load" on the circuit, so leave the start relay hooked up and "back probe" the connector. You should have "same as battery" in start, and it should pull in the relay and crank the engine if in park or neutral

2--IGNITION BYPASS Hook your meter from coil+ to ground In start, you should have "same as battery," and in no case less than 10V

3--IGNITION RUN. Check this circuit one of two ways.

THE HARD WAY, possiblly easier to understand. First carefully measure battery voltage with key off and note. Next, hook your meter to the blue alternator field connector and turn on the key to "run", read the voltage. Subtract the two to see how much VOLTAGE DROP you have in the ignition harness. You should have a difference of NOT MORE than .3V (three tenths of one volt)

THE EASY WAY. Clip one meter lead to the blue alternator field wire, and clip the other to a battery source, IE the stud on the starter relay. Turn the key to "run," engine OFF. You are hoping for a very low reading, the lower the better. You do NOT want to see more than .3v (three tenths of a volt)

cudacarl
01-08-2013, 01:37 PM
chirorod

then my voltage readings would sound correct.

in start i have 12v if i read from coil positive to battery negative.

in start i have 9v if i read from coil positive to coil negative.

i have no problem with the run circuit or the starting circuit. i just brain farted when i originally started the post about the yellow wire. its been a while.

when i originally started checking all this i was getting less voltage. once all back together i got more. i'm still suspecting bad connections.
won't have time till the week end to clean things.

440roadrunner
01-08-2013, 08:29 PM
Your top suspects for bad connections are

the bulkhead connector

the ammeter and it's connections

the ignition switch connector and the switch

and in very rare cases, failure of the "in harness" splice which is on the black ammeter wire under the dash. If you get to where you suspect it, you'll have to cut or untape a few inches of harness, working down the black ammeter wire.

chirorod
01-09-2013, 07:25 AM
you have a 3v drop across the coil. that's normal, internal resistance of coil.
I second the motions that there is a bad connection at the the bulkhead connector. Might have to file the male ends, and replace female ends. They are very prone to corrosion. Should have 12v at coil in start position.