ign problems

[alfred]

hey guys,i hope someone can help me out..

i had my 72 dart running a week ago and now the dart wont start anymore ?

ballast resistor is new...

coil is new,i tried another one with no luck.

i have a very weak spark.

i have 9 volt on the coil and drops to 6 when starting.

maybe it's the ecu( black one) ??

how to test if the ecu is down?

or maybe the resistor is down again,it's a 4 pin resistor(can i check the resistor to if it's good or bad?)

thanks,

alfred

[Mefirst]

If you have another ignition box change out the one in the car and check if it helps, also try to change out the resistor.

Befor you do that you chould check this...

If you get the engine to start, check the voltage at the alternator. May be that your alternator is not charging for some reson, check the FLD wire connectors, maby a bad connector. Check voltage at the battery, if battery is full the voltage should be over 12.6 volts something, if alternator is charging the battery the voltage should be close to 13 volts. The starter solenoid might be busted???

I think this about covers it...

/Tom

[alfred]

If you have another ignition box change out the one in the car and check if it helps, also try to change out the resistor.

Befor you do that you chould check this...

If you get the engine to start, check the voltage at the alternator. May be that your alternator is not charging for some reson, check the FLD wire connectors, maby a bad connector. Check voltage at the battery, if battery is full the voltage should be over 12.6 volts something, if alternator is charging the battery the voltage should be close to 13 volts. The starter solenoid might be busted???

I think this about covers it...

/Tom

hey tom,long time no see..all fine over there?

ok,charging is fine,that's not the problem.

last week i replaced the resistor because i had only 4 volt on the coil...after that the engine did run..

maybe it's the same problem now?

how to check if the ballastresistor is down?

maybe it's the ecu,i have no spare.

so....i'm not so good with these electronic stuf so i hope i get some help here to clear this out.

thanks tom

alf

[Mefirst]

Alf...

The only way to measure if the resistor is working is to measure its resistance, amps. What the amp (resistance) of a working 4 pin resistor is I have sadly no idea.

Do you have another coil you can test? I don't think the coil is at fault, but one never knows. Also check the wiring under the dash, if I remember correct the coil positive wire is either the Brown or Blue one that comes out from the ignition lock.

To know if the ECU is down there is no way of telling cause of the low voltage (weak spark), 4 volts will not be any where near enough for the ECU to work.

I don't think there is anything wrong with the ECU or the coil. The problem is the low voltage, you don't have any where near the needed voltage. -You need to find out why? So check and double check the wiring so you know for certain the alternator is charging, measure volts at the alternator, on both sides of the resistor, at the starter solenoid, at the battery... Check that the small "brusches" or what ever they are, right under the FLD connector, also check that the connectors are good. I had once had a bad FLD connector and that resulted no charge and the engine just died when the battery went empty. Took some time to locate that problem... Check the battery that it has not gone bad for some reason?

With electrical problems there is no room to presume anything, you need to check everything, reason is that the problem does not have to be a big one to make electrical stuff ruin your day...

/Tom

[Nacho-RT74]

Alf...

[Nacho-RT74]

i have 9 volt on the coil and drops to 6 when starting.

SHOULD IT BE 12 volts on START position since is  DIRECT FEED FROM BATT, AND 9 volts on RUN position with cold engine when power runs through ballast up coil

how to test if the ecu is down?

Check pin 4 with chassis. it must be continuity, however could it be still bad, but is at least one check without test module.

or maybe the resistor is down again,it's a 4 pin resistor(can i check the resistor to if it's good or bad?)

Low resistance section it should be 0.5-1.5 ohms.

High resistance 5 ohms.

[alfred]

Alf...

hey nacho,how are you doing.....

nice picture of me

thanks for the help,see what i can do with your info.

thank u tom and nacho

[alfred]

i have 9 volt on the coil and drops to 6 when starting.

SHOULD IT BE 12 volts on START position since is  DIRECT FEED FROM BATT, AND 9 volts on RUN position with cold engine when power runs through ballast up coil

how to test if the ecu is down?

Check pin 4 with chassis. it must be continuity, however could it be still bad, but is at least one check without test module.

or maybe the resistor is down again,it's a 4 pin resistor(can i check the resistor to if it's good or bad?)

Low resistance section it should be 0.5-1.5 ohms.

High resistance 5 ohms.

okay,last q: witch one is pin nr 4 and how much volt does it need?

alf

[Nacho-RT74]

no voltage... CONTINUITY with chassis.

here is a frontal view of PLUG ( not module ) so just reverse it... is one of the pins what feeds the distribuitor.

Pin 3 is the one eliminated on 4 pins modules

[Nacho-RT74]

hey nacho,how are you doing.....

everything fine

nice picture of me

naaaaah... unless you will dance Tango, the rose on mouth is some "weird"  

[Mefirst]

Nacho** I think the ment the ballast resistor...

[Nacho-RT74]

Probably, but I MEANT ECU module when I talked about THE 4TH PIN


about ballast:

If there is not enough juice at coil on RUN position, yes it could be damaged  ballast, but on START position, ballast is bypassed so definitelly it should get 12 volts or so at coild driectly from ignition key. If there is not that power, then is a problem on wiring, or kinda weird short...

Shorted ballast maybe ? just if on back of ballast the resistance spring lost the ceramic filler and maybe power is being sligthly shorted with firewall somehow.

[alfred]

maybe i have to get another battery to,i don't know how old this one is....

maybe it lost power after yrs?

what battery do i need,howmuch startamperes etcetera?

1972 dodge dart 318 engine.

alfred

[Nacho-RT74]

Power from ignition key to coil on START position is bypassing the ballast but ARRIVES anyway to ballast since is spliced there ( brown wires on ballast ). So if there is a short on ballast making that power droping still will get the problem even on start. If you see at ballast, you will see two brown wires spliced on same prong... one comes from ignition key and the other one goes to coil.

You can try to start the engine feeding directly the coil from batt with a direct wire. If Your ECU module is 4 pins one, not the 5 pins one,  you can in fact unplug ballast and check what does happens. Should start without problem and you will get max juice at coil on start and run position.

Works like a test and in case of emergency on road, but is not safe to coil drive long time on that way with full power... causes overheat on coil

If starter motor is cranking then you have juice to start the engine, that's all... you can have an old batt but for a while is able to crank, then should start.

[70charger_boy]

Check you're engine ground wire.  Is it bolted on a painted surface?  If it is that is your problem.  Simply sand the area that you will bolt on grounding wire.  You need 11 1/2 volts to turn over the motor

[alfred]

still not able to do working on the dodge....2 days ago i hurt my back....some cracked inside and the only thing i can do is walk around like a oldtimer

i let u helpful guys know if i can work it out with the dart.

alf

[alfred]

no voltage... CONTINUITY with chassis.

here is a frontal view of PLUG ( not module ) so just reverse it... is one of the pins what feeds the distribuitor.

Pin 3 is the one eliminated on 4 pins modules

ok nacho,i checked the nr 4 pin....there's 0.2 volt.

and i measure 9/10 volts on both sides of the coil?

thats strange to...

i think the ecu is down,i can get another one to try before buying a new one.

see how tht works out.

[alfred]

ok,got it running with another ecu

i have a black ecu,can i use another one to,i have a 4 pin ballastresistor.

i did read somewhere that the black ecu needs 4 pin ballastresitor

[Nacho-RT74]

5 pins ECU uses ONLY double ballast resistor

4 pins ECU uses single ballast resistor but can be used with double ballast resistor, just the secondary resistance will be unused. The green traced red wire will arrive to the empty pin space.

Good you found

[alfred]

thanks nacho, have to find another ecu to..the guy wants his spare ecu back

[Nacho-RT74]

OK great but just couple of questions

ok nacho,i checked the nr 4 pin....there's 0.2 volt.

I don't know how you were getting that measuring or how you were testing... Volts ? should it be OHMS. Multitester measurements takes between pin 4 and chassis ( body ground )

as stated is only a way to test without a bench ECU tester, but that doesn't mean assure you is good or bad at all.

and i measure 9/10 volts on both sides of the coil?

As far I know ( never have measured it ) - side of coil should it be NEGATIVE not positive and should it be pulsating, since circuit is closed every time reluctor point pass in front of pick up coil inside distribuitor, making the SPARK than rotor routes.

about + side of coil, is good get 9-10 volts in cold with ignition on RUN position.