Ignition problems: ballast resistor, oil, ignition module

[class87]

From: lucidsodemite  (Original Message)
Sent: 6/24/2008 5:16 PM

i replaced my stock coil and wires as well as cap and rotor with an msd blaster 2 coil. i wired it in reverse somehow and shave since corrected but now i am having issues with the motor not starting. i at first thought it was the ballast resistor and have replaced it a few times. no help. i then tought it was the coil maybe i burnt it out putting the wires on backwards. i was told that was probably no the case. but i could have burnt out the ignition module. i have 2 used modules and i tried them both and voltage at the coil is better but it still wont start. it is a 1976 brave 22 ft with a 440 dodge. any ideas? i have 13 volts at one end of the ballast resistor and then on the other end the green wire that runs to the ignition and voltage reg has the same 13 volts bu the 2 pink one goes to coil other back in to the harness and i suspect back to the ignition there is 1.2 volts and when i change the ignition module i get 4 or 3.5 volts. do simply have to get a new ignition module?



From: denisondc
Sent: 6/24/2008 7:53 PM

I dont have much insight here. I agree the coil probably doesnt care which way it is wired in - its just a step-up transformer. The 12 volt feed for the ignition from the switch is really two wires. On my 72 there is a 16 gauge red wire, that is ignition circuit 1. It provides 12 volts to the ignition resistor when the ignition is one - and from there to the ignition module I believe, as well as from the far end of the ignition resistor to the ign. coil. Also on mine there is a 14 gauge pink wire, that is ignition circuit #2. This one is only used when you have the ign. key in the 'start' position. It bypasses the ignition resistor to provide more current to the ignition coil when the engine is being cranked. I -think- the engine wont start if the pink wire is broken. I know it is pink, and have followed it all the way from the ignition switch connector on the steering column, down to the back upper end of the motor. Unfortunately that same wire is listed in one of the common wiring diagrams as being 'BK', which stands for black, instead of PK for pink.
The actual signal to make the starter turn comes when the orange wire from the ignition switch to the starter relay is grounded inside the ign. switch.
We have had several members who engines would always start, but die as soon as they let the ign. switch go back to the 'run' position; because either the red wire was broken, or the ignition resistor had one or both of its resistors gone bad, or the contacts inside the ignition switch were bad.
Another thing that can prevent the mopar electronic ignition system from firing is if the pickup coil assembly inside the distributor is bad, or its little connector (between the distributor and the ignition module) was bad or melted.



From: DaveVa78Chieftain
Sent: 6/25/2008 10:48 AM

For reference at ballast resistor:
1 pink wire - goes to the "+" side of the coil.  Normal running voltage is reduced by ballast resistor.
Other pink wire - goes to "Ignition 2" side of ignition switch.  Used for 12VDC to coil during "starting" only.
Dark Green wire - goes to Electronic module but is only used for low RPM compensation.
Both red wires - are 12VDC supply - "Ignition-1" from ignition switch for 'Run" (they are soldered together in harness)

For reference at Electronic Control unit (5 pins):
Red wire - is 12VDC (Also soldered to the 2 red wires for ballast in wiring harness) - "Ignition-1" from ignition switch for 'Run".
Yellow wire - firing signal to coil ("-" side of coil)
Dark green - The compensation voltage from the ballast resistor.
Brown/White and Green wires - firing signal from distributor.

Here is the Electronic Ignition Reference Information

I have heard that some autosupply houses can test your Electronic Ignition Module.
You can also purchase a Actron Ignition Module and sensor testor to test the module.  I originally bought one to check Oxygen sensors so they are multi-purpose testers.

Dave



From: lucidsodemite
Sent: 6/25/2008 1:22 PM

yes that is the layout but does anyone have any idea why the unit will not start when all i did was switch out he coil and plug wires and cap and rotor. would wiring up the coil backwards blow the module? i switch to a different module and voltage at the coil increases but still is not 12 volts. any ideas.
 


From: DaveVa78Chieftain
Sent: 6/25/2008 2:39 PM

Voltage to coil ("+") during normal running is not 12VDC.  Only time it's 12VDC is when starting (ballast is by passed).  It's possible the ignition module was damaged.
For electronic ignition, with key ON, engine not running, there should be basically 12VDC (neg meter lead to ground) at both coil posts.  Thats because there is no current flowing through the coil.  You just see the battery voltage potential.  You do not 'see' a voltage drop (do to ballast resistance) until current flows through the circuit.  When running, the ignition module pulses (opens/closes) the circuit ('-' side of coil) based on the distributor signal.
Make sure rotor and cap are correctly seated.  As shown in the diagram I linked to, there is not much to this circuit.  Make sure the body of the coil is grounded.  The secondary side (spark plug) is grounded through the coil body.
The one thing I do read about the Blaster 2 coil is that it requires a 0.8 ohm ballast resistor.  The stock ballast resistor is only 0.5-0.6 ohms.  That small of a diff shouldn't matter though.



From: lucidsodemite
Sent: 6/25/2008 3:38 PM

i do not have 12 volts at the coil at any time. as previously stated. there is 1.5 volts at the coil on the old ignition module and 5 volts at the coil when i switch in the used module i got. there is 12 volts at both red wires going into the ballast resistor and 12 volts at the green terminal of the ballast resistor but again only 1.5 at the pink wire. same at the coil. when i switch the modules it goes up to 5 volts but that still seems incorrect. the unit is spinning over well but wont start seems like no spark. i have printed off the link you provided thank you. i will go through some of the tests and see what comes of it. i checked for a wiring diagram on the site here but it only seems to go to 1971. mine is a 76 is it the same? 



From: lucidsodemite
Sent: 6/25/2008 3:39 PM

does the ignition module have to be grounded? does it have to be bolted down to work properly or can i just hook it in and test?



From: denisondc
Sent: 6/25/2008 5:55 P

The basic wiring for the ignition system on your 76 would probably be the same as it was for the earlier models, though the colors of the some of the wires may be different; but mopar (in the 70's anyway) was usually consistent in the colors they used.
The ignition module doesnt have to be bolted in place, but it must be well grounded to the block - otherwise it may not reliably sense to the low voltage +/- trigger signal from the pickup coil inside the distributor.
Anytime the engine is cranking or running, the voltages on/across the coil will be complex ones (unless the ign. module is dead); with an a.c. component superimposed on the d.c. component. These are hard to examine with anything other than an oscilloscope.
I will send you an email with the 2 halves of a chassis wiring diagram for the 1974/75 Dodge chassis - and you will be able to see they arent greatly different from the 71's, other than having the printed circuit for the gauge cluster. These 2 jpegs are from the www.mytravco.com site, which seems to be off-line recently.



From: lucidsodemite
Sent: 6/25/2008 10:20 PM

how is it grounded through the block? is that acheived by bolting it down? 



From: DaveVa78Chieftain
Sent: 6/25/2008 11:25 PM

The ignition module is grounded via the mounting bolts.
Pink wires (coil '+' side) are on battery side so they have a steady voltage.  With key ON, engine not running, voltage is routed through the ballast resistor.  When you place the key in 'START' the ballast resistor is bypassed (the other pink wire) and 12VDC is applied to the coil ('+' side).

signal path:
key ON: battery to ign sw to ballast resistor to coil to ign module to ground.
key START: battery to ign sw to coil to ign module to ground.

ignition module is basically an on/off switch controlled by the distributor pickup.

T/S procedure is contained in the link  I provided.

Dave



From: lucidsodemite
Sent: 6/26/2008 1:23 PM

Than' s dave that is actually clearly explained. i appreciate it. i will begin to comb through this mess and see what is up.



From: lucidsodemite
Sent: 7/2/2008 1:52 PM

Hey it works now! i combed through more of the wiring and found a number of bad connections and go nowhere wires. removed or repaired as neccesary, cleaned up a few grounds and tightened up some loose wires and all of a sudden voom it started. dont know what was wrong exactly but now it works and i cant seem to make it fail so hey hey! thanks for all of the advice and especially thanks for the troubleshooting guide and wiring diagram.



From: TripleNickel2
Sent: 8/14/2008 9:20 PM

I'm fighting the same battle with the new to me '73 Chieftain.

I just need to get it running long enough to get it home so I can dig into the wiring. The '73 had a bad exhaust leak on the driver's side and has done a lot of damage to the wiring in that area. The exhaust leak is now fixed, so that part of the battle is won.

The PO wanted to demonstrate how he could get it started by using another battery, grounding it to the block and jumping the positive side direct to the coil.

Well, that never worked and I've never been able to get a spark from the coil.

Working through Dave's troubleshooting guides I've found the coil pickup to be bad (something like 4 ohms when the test range is 400-600 ohms) and replaced it.

Voltage is still very low at the two red wires to the dual ballast resister (I'm sure a function of the melted wires) but I can jumper 12 v to there and the rest of the troubleshooting guide tests fine on connector cavities 1, 2, and 3.

No local parts place had an ignition module in stock today so I'll have to wait until 9 am tomorrow when their PDQ delivery arrives to see if the ignition module is the cause of no spark from the coil.

If the ignition module doesn't solve the "no spark from the coil" problem, does anyone have any other ideas?



From: TripleNickel2
Sent: 8/15/2008 11:53 PM

Follow-up:

The ignition module did the trick. The Chieftain fired right up!

The 45 mile trip home was marginally uneventful if you don't count the vapor lock about 30 miles into the trip and away from the curb lane...but that story will have to wait until another day.



From: denisondc
Sent: 8/16/2008 8:26 AM

I began having vapor lock in hot weather (over 100°f); it was worse at higher altitudes, (like Las Cruces NM ~ 4000 ft I think). Having a look underneath I saw two places where the fuel line was close to & in view of the exhaust manifold; and that the aux. fuel tank (the frontmost one) was close to the exhaust pipe & muffler. I put aluminum heat shields to block the radiant heat of the exhaust manifold from 'shining' onto the fuel line, and from the exhaust pipe onto the side of the aux. fuel tank. My vapor lock problem was Gone, at all altitudes and in all temperatures.
The main fuel tank came with the 'bare running chassis' from Dodge, and had a heat shield next to it already. The aux. tank was added by Winnebago, and there was no sign there had ever been a heat shield there.
I had added a fuel pressure gauge to the dashboard when I first got the RV. It tells me when to switch fuel tanks, & when I should replace my fuel filter, but mainly gives me peace of mind when I am starting across a long bridge, into the concrete maze of a large metropolitan area, or into a tunnel. The filter can last anywhere from 8000 miles to as little as 40 miles before it clogs up. It depends on how lumpy the interstates are. And because of the way the fuel press. gauge responds, you can tell the difference between vapor lock and a slowly clogging filter.