68 Coronet Starting Issues

Hey guys, hoping you can help me out here.  I picked up a 68 Coronet 318 car.  When starting the car sometimes it clicks when turning the key to on position (which would indicate the starter).  Other times nothing happens at all, silence.  Most times by putting the car in neutral, it starts no problem!  Recently that doesn't work either.  If you boost the car, it starts no problem again.  Battery is brand new.  Any thoughts?  Starter?  Relay? Neutral safety switch? Ignition wiring?  Don't know where to start first?

Thanks as always for your insight and experience!!  

check the grounds first, battery to body,body to motor,then when it does nothing at all,have some one turn the key while you put a test light on the relay terminal (going down to the starter solenoid) usually brown, after that back probe ign. switch start terminal. but it sounds like a ground issue.  

Thanks Quaterfish.  Never had a 318 before.. where is the ground to body on those engines.  Ground off battery is sometimes on rad support, but it's not on the firewall on this car.  

Yup, should be firewall to back of cylinder head, if not there make a ground strap up, from motor to anywhere on the body/frame.  

check all connections for being tight. battery negative to front of head and to rad bolt. u can bypass the neutral switch for testing for free. my guess is a bad connection or starter. let us know.  

Ok, changed the starter relay, changed the alternator, put a new ground strap from passenger head to firewall, put new connectors and wire from starter relay to neutral safety switch.  Nothing.  If I boost it, starts and turns.  The second I take off the positive cable or put my foot on the brake, it stalls!????????
I don't have a ground from negative termimal to the rad supoport.  Now it won't start in neutral either.  Has to be boosted.  It's almost as if it's taking a ground from the boost to allow the start.  But why is it dying now when you take off the cables or draw any sort of power??  Talk about weird???  

Sorry, one more question.  This car is an all original 318 car (points).  I put a solid state voltage regulator on.  The alternator is now a dual field, but no ground connected to anywhere.  Could that cause my problem?  If so, where would I ground the alternator to?  

Thanks again guys.  I appreciate your input!  

Well, pulling off the cables is not the problem, you said it was a new battery,but I have seen alot of new batteries that are duds, I would start by load testing that battery,use a VAT-40, or associated model 6029 will work fine, it would be even better if you have access to a midtronics tester, that is the standard for battery testing here in a chrysler dealership,(so if you know any Chrysler techs,sorry I am in PA.) see if you can borrow it, it will break the battery down for you by CCA for the given voltage, turn the headlamps on for 10secs. before testing to get rid of the surface charge then hit it with a full load from the tester for 10seconds, look for voltage to drop more than 2volts and the battery is junk (during the load part of the test),also when you have it running put a volt meter across the battery to see it the car is charging.  

ok...   first thing..    never pull a battery cable off while the engine is running..  this will destroy most alternators.. and many voltage regulators...

you are working on several different systems at the same time.... the charging system only keeps the battery charged...

the battery is used to supply current to the starter...  it also supplies current to the car when the alternator is not spinning enough to handle the complete load.....   so when the car is idling..  you have the defroster fan on..  the wipers on.. the stereo on.. the head lights on..    the alternator at idle cannot make this much current.. so it pulls it from the battery..  since most cars don't idle for long.. as soon as you start driving.. the alternator can pick up the load.. and charge the battery..

first... you need to test you car with a fully charged battery..    charged on a battery charger for at least an hour at 10 amps..

digital volt meters are needed to test cars now a days.. this is 2009...   digital volt meters start at 5 bucks..

after you charge the battery..   put it in the car..   turn the head lights on for one minute. then shut them off..

with your digital volt meter set at 20 volts DC scale..

measure the amount of charge on the battery...

12.65 volts.. is a 100% charge..
12.45 volts is a 50% charge..
12.25 volts is a 25% charge..

you have to test the car.. both starting and charging with a fully or close to fully charged battery..  unless you like chasing non problems..

the battery cables have to be clean and tight..

start the motor..     if the charging voltage now is over 14.1 volts.. you have a good charging system..

now. it is also important to spend another minute.. with the engine running.. turn the head lights on also..

with your volt meter set at 20 volt DC scale..

touch the negative battery post with one test lead...   touch the other to the engine...   block.. head.. intake..

you should have less than 0.02 volts...   you might have as much as 0.05 volts..

now.. touch the negative battery terminal and the other end to the body...  again.. you should have less than 0.02 volts

if you get any thing more than these readings...   you have a ground problem...

remember.. you are measuring the difference in voltage...  since you are on the same side of the battery.. there should be little difference...


one the charging system..    more to come/..  

on the charging system...


the mechanical voltage regulator...    this pulses the positive  to the alternator field connector... the other is grounded...
so the pulsed power controls the magnetic field in the spinning rotor....

on the electronic voltage regulators..  the voltage regulator pulses the negative side  to the voltage regulator case and through the hold down screws..

the power is supplied to the rotor through the other brush connection...

so you have several choices..      if you want to keep the mechanical voltage regulator..   and the car is wired for it..

make a jumper lead to ground on the non used connection...     if you examine a single terminal alternator.. that brush is just grounded through the screw...      with 2 contacts...  both are isolated from ground..  

anything else...?????

oh. the starter circuit...   i think that since you jump the car and it works... that you really don't have much of a problem other than possibly a discharged battery do to the alternator not charging..  

Thanks Waynep, I appreciate your help and time in writing this out for me!  I'll go through that over the next couple of days and get back to you.  The thing that really bogs me is why it used to start in neutral but not in park (unless it was a total fluke???).
I'll put another battery in and see what happens from there.

Thanks again.  I'll keep you posted!  

i missed that...

the neutral safety switch is threaded into the side of the transmission....

it has one wire on some... really early units.. but most have 3 wires and is actually 2 switches..

when the transmission is in park or neutral...  the center terminal should be grounded... but the shift linkage has to be properly adjusted..    sometimes... you just have to replace it.. the internal contacts do wear..

if you look at the starter relay on the firewall...     there is a big stud... that is hooked to the battery  positive..

the center terminal with the machine screw to hold a clamp down ... that goes to the solenoid connector on the starter..

then there are 2 push on terminals...

one comes from the ignition switch...  that gets power when the key is turned to the start position...

the other runs to the neutral safety switch on the corner of the transmission..  these are connected inside the starter relay to a coil of wire...      when the transmission is in park or neutral.. the switch is grounded...  so anytime power comes from  the key... the relay will work....   when the trans in not in park or neutral..  the circuit is open.. so nothing happens..

what i have found... the transmission lever is in park... but the parking prawl rod has not been able to push the lever into the parking gear on the output shaft..  this keeps enough pressure on the transmission manual lever to keep it out of the proper detent for the neutral safety switch...


if you want something to compare..   look at the side of a cube relay.. or ISO relay.. normally found on cars...

the big stud is pin 30
the middle machine screw hold down. is pin 87a

the push on terminals are pins 85 and 86...

there are some later mopar starter relays that have 3 push on terminals .  those are wired slightly different..

and an earlier version..  that has only one. as the one of the push on leads is actually grounded to the case...

on a different point.. the amc. cars with a torque flight have the neutral safety switch on the trans.. that  wire connects to the back of the starter solenoid.. the weird looking ford style but with an angled bracket.. and a 3rd push on connector on the back side..  

Thanks  WayneP, I really think that's the problem.  The neutral safety switch on the torqueflite is a single wire with a nut on the back of it.  It's a brown wire that goes to the bottom left push on terminal of the starter relay. This relay has 2 push on terminals, the big positive and other screw in terminal for the starter.  I actually had to make a new wire because the plastic cover on the terminal was melted at some point. Still making contact, but fried at some point before I got it.

Any thoughts or time on how to adjust the shift linkage? (in case I need to go down that road).

Again, thank you!!!!!  

Hey WayneP and others,,,

Good news... I got it started.  Not sure which one worked, but I adjusted the linkage to the neutral safety switch and also put a ground wire from the 2'nd field on the alternator to the case itself. That seems to work, but after shutting it down the battery didn't have enough power to crank.  I guess everything ran off the battery for a while prior and killed it.  I put in a back up battery and seems to be working find now.  Fingers crossed those two things did it!

Thanks again for your help and advise!!!  I appreciate it!!