Mopar Muscle Association UK

Dave's right, the ignition switch is a bugger when it fails, made my car carry on cranking even when in run position, and then just stopped giving power anywhere.
Got a decent test meter?

but thankfully

these cars are easy to hot wire

1 bullet jumper lead 2 two bullets about 2 inch long and a flying lead for starter

electric comes in on 1 lead needs to go to two others and the 4th is the starter circuit


when chacking which is which

make sure its not in drive

Dave

HAD THIS HAPPEN ON MY OLD 78 DODGE PICK UP
swapped the ignition module over from my mates 68 Cuda and blew all the stock gauges in the truck
it still would not start got a new module, still nothing...ended up being the ballast resistor swapped in a new one sorted ???

Just a warning... be careful with the module swapping, dont know why this happened... but it did in a Flash, literally and all new gauges needed

OK Gurus - Here is the latest. Did some proper investigation tonight and the results are very strange indeed.

Essentially the components appear to be working as they should (voltage reg passes through (which is all you can expect with no alternator) and the ballast appears to drop the voltage. Trouble is the voltage is nowhere near where it should be.

Its 12v over the battery (obviously) - but everywhere else it drops to about 5. Just makes no sense....

A sinplification of the ignition system is thus (see diagram). At all points I am measuring over the coil. Up until step5 I had assumed my investigations were pointing towards not getting enough voltage being supplied from the dash - But then I went straight from the +ve to the volt reg - still got the same results.

So even when I bypass both volt reg and ballast I still only see 5v at the coil??!? huh ?

Of course what my diagram doesnt show is all the ECU hanging off the -ve coil etc. So does this mean it MUST be in there somewhere ? How can it be - AdeW has tested ECU and it fires.

Oh, and yes - I have checked all my earths - even made auxiliary straps to double check.

Any other checks ? Getting very sad now...

Pull the bulkhead connectors for the engine loom off and put the meter onto the spades in the connector block and see what readings you get then.
Have you tested the voltage at the steering column where the large
flat conn block is?
Give us a tinkle at work in the morning mate, two heads etc

something is eating volts

either you have a pretty resistant short circuit somewhere which is eating half your volts and i guess getting hot and smokey i.e you'd smell it

or your fuse box and bulkhead connector have become victim of the last round of humid and damp weather. great potential for this as the car has not been used in any great way for 2-3 months

clean up all connectors to shiny brass with a small file dremmel or dudicius use of small bits of rolled up wet-n-dry
wd40 them
vaseline them

put em back

open up fuse box

find incoming wires
think its a fat blue and fat orange, one for running the car one for running the accessories. these come from the 4 pin connector at the back off the ignition key lock
these split off into two seperate input sections of the fuse box
1 will have way more fuses connected to it than the other

check voltage between connector of each fat wire and car body

should be 12+ with motor running
11-12 with motor off

then systematically

clamp the -ve of you meter into a good earth on the body to give you freedom to do the rest

meter on
+probe
onto the end of the fat wires into fuse box 12
onto the connector for the first fuse 12
onto the end cap of the first fuse 12
onto the other end cap of the first fuse 12
onto the connector at the other end of the first fuse 12
repeat for all fuses....12

this proves
battery- ignitoin switch to fuse box and onwards is good... as any short cuircuit going off from the fuse box down the line would pull voltage down across the lot of fuses on that feed until the fuse it was on burned out

if you have cleaned bulkhead connector it should not be an issue
the connectors were laccured orginally and it is scraped off on the areas of contact only. since these things have been pulled and put backl togheter over 30 years you now have just exposed brass which like a tuba tends to go a bit green if not given a quick buffing every now and again

any way if you have not uncovred your issue yet it it isolated to ignition /charging circuit

next option is to rig it so it works circumventing your current wires

this can be done using a 12 volt feed from batttery to a house light switch (13 amp) and back to the ballast input(s)

if it all works its the wires into the ballast at fault

if you want to risk it stick 12 volts direct to the power feed for the ignition box and coil

if it works

then ballast resistor and on ward wires are at fault

if need be i can lend you a set of industrial push to make and lock to make 60 amp swicthes...lend you cos they cost 60 quid each new

these were off a lead rolling mill and accidentally fell into my toolbox for just this purpose

1 for starter
the locker for ignition

will get you to the NATS

but kinda makes the car easy to steal

Dave

Ade - Will do

Dave - Will do also. Although given item 5 above (where I jumped the +ve straight to the voltage reg therefore feeding 12v directly to it, bypassing the dash completely) it would seem to imply the voltage-muncher is in the ignition somewhere...

Does that make sense ? 12V delivered direct to volt reg has been munched down to 5v by the time I measure at coil.

Tonight I will jump coul to +ve just to prove spark (this will be fine I am sure).

Only thing left if that ^$&^%$ ECU again ???? Which means its now eaten 2 orange boxes and a blue-generic one.

Alternator and volt reg changed, so shouldnt eat any more - but SOMETHING is munching the volts. Something in the ignition circuit - and I dont think its regulator or ballast. Not much left :shrug:

Anyway - Will try as you suggest.

Have you replaced the 40 year old wiring that could be chafing on the bodywork?
Run an overlay system in and then test....

see i'd expect to see 5 volts off the field connector on the voltage regulator at idle when the battery is charged

i.e it powers the alternator at idle to put out a trickle charge

once you battery gets a bit flater the volatge off this pin increases driving more current through the coils in the alternator thus making more charge (from the rotary energy provided by the running engine) to top up the battery again

sure you have it wired correctly?

showing me a picture is no good as my 1970s aussie mopar is basically a 1962 valiant in all but body...yours is kinda like magic rocket science

with its new fangled ways and that

Dave

hope you get it sorted morgan -

If your really in the hole withthis Paul at AMCAR near Bicester 01869 -601028 is an electonics whizz though its means paying out. Not sure how much help he might give you on the phone. He's not 2 far??

Thanks Mike.

For the rest of you its moved on a little. Getting my 12v out of bulkhead. ( good). Everything pointingnback to module again when i decided to jump coil direct just to ensure spark -nothing. And now i get no readings at all from it !

So - looks like coil may be fried (too)

For the money this is going to cost I can near-as-dammit rip it all out and put a self contained dizzy/ecu/reg/12v setup in...

The difficulty with isolating this is being unable to test components. When someting is physically broken you can see it to fix. With this, there are multiple potential sources. What you need is a running setup on a car or test bench where you can plug bits in until you find the one that stops the car.

I'll get there. But its maddening in the meantime....

Thanks Mike.

For the rest of you its moved on a little. Getting my 12v out of bulkhead. ( good). Everything pointingnback to module again when i decided to jump coil direct just to ensure spark -nothing. And now i get no readings at all from it !

So - looks like coil may be fried (too)

For the money this is going to cost I can near-as-dammit rip it all out and put a self contained dizzy/ecu/reg/12v setup in...

The difficulty with isolating this is being unable to test components. When someting is physically broken you can see it to fix. With this, there are multiple potential sources. What you need is a running setup on a car or test bench where you can plug bits in until you find the one that stops the car.

I'll get there. But its maddening in the meantime....

Test.

Right. The diagram posted. Let me see if I can help you test this correctly.

Replacing one bit at a time is NOT the way to do it!

Remove the multi-plug from the orange box unit. When you look at the plug connections refer to the diagram i just posted so you kow which socket in the plug I want you to test.

Turn the ignition ON.

Ground the -ve lead on your voltmeter and connect the +ve lead to #1 terminal on that plug. It is normally a blue/yellow lead going to that terminal. The voltage should be within 1v of battery voltage with everything else in the car turned off. If it isn't you have wiring problems.

Do the same to terminal #2 with the black/yellow wire. Again voltage should be within 1v of battery voltage.

Now check terminal #3 IF USED. Should be within 1v of battery volts again. Not all set-ups use this terminal though.

If you look at that diagram you ca see that these tests are checking both the coil and ballast resistor. Note also how the resistor is by-passed to terminal #1.

Turn the ignition OFF.