i found 1.6 ohms resistance between positive at coil and white wire at icm,should that not be the red wire??

 

Yes you should have between 0.8 and 1.6Ω on the red wire at the ICM on the vehicle side of the harness with the ignition in the off position and the ICM unplugged.

We need some background info here. Was the vehicle running before ? Or did you just get this vehicle. Again is it an E350 Cab and chassis Class C type unit.

We can not really help you with wiring issues UNTIL we know what it is you have...

 

First paragraph rebuttal:
Getting the trucking does identify the problem as one of three possible problems. Plus it is good for moral.
Getting the truck to stay running without hold the key to the "START" position is an improvement and not a waste of time. Also the ALT should come online and charge the battery.
He is current running with the key in the "START" position, which also has 12 volts to the coil positive, so what is really different here compared to running a jumper wire to the coil positive.

Smoke method of electrical diagnostics:
It is commonly know in the electronic community that "smoke" is what make stuff work. Once you let the smoke out of any electrical device it just stop working. So just follow the smoke to the defective electrical components.

Jim

 

The wire color swaps in the connector which powers the DS2 IGN module, so yes it is the white wire when you have it unplugged.
Take a good look at the connector when it is plug in and you will see this.

Jim

 

Again this NOT helpful and a complete waste of time.
First off we do not even know what vehicle this is.
Second, it does not identify ANY problem as all it is doing is bypassing the problem.
Third the vehicle already runs just NOT as it should, jumpering stuff out to make it run accomplishes ZERO and if the issue a maladjusted ignition switch or fault in the circuit the alt will charge still charge you are back feeding the Run circuits accomplishment ZERO
Fouth we are NOT dealing with a PCB and milliamps where if you smoke some thing it will be the faulty component this is multiple hundreds of amps potential that may torch a wiring harness or the ballast resistor that may require many multiple hours of work to repair the damage and obtaining obsolete parts.

This is the most irresponsible way you could this to that accomplishes absolutely nothing.

Electrical diagnostics have a procedure and a sequence to fault find simple as that...

 

i will run a hot wire to icm and try to eliminate key switch circuit ,i have tried my old icm with the same result,truck was parked for 5 years when i bought it ,i hooked up to an external fuel source to get it started it ran but badly so i switched to a new carb,now it runs awesome but has the electrical issue

 

i dont understand how i can have power to coil in run but not to icm

 

This can be resolved but it going to take proper step by step diagnostics. And the FIRST thing you need to do is TELL US WHAT YOU ARE WORKING ON....

 

i am working on a 1984 ford E-350 chassis C class motorhome

 

Ok least we got that sorted.

Next step disconnect the ICM power connector. Check for power at the coil. in start should be 12V In run should be 6-8V

Do that and let us know the results. We need to do this to verify the integrity of the wiring to the coil.

 

See post 4 and 5 for this information.
It seems that the "just have you chasing your tail" guy already asked this question.

Jim

 

Do tell was the ICM disconnected when the coil voltage was checked? Thanks for pointing out the obvious, but do try to keep up...

 

Sure, not problem, I am happy to help.
Back in post 5 the OP stated that the coil voltage was 7.45 in run and 12 in start.
The 7.45 volt reading provides a whole lot if info, listed below.
1: The coil horseshoe connector and the both connectors on the DS2 module were connected in the ready to run configuration.
2: The single ground for the entire Ignition System, located inside the distributor, is good.
3: The DS2 ignition module is being powered ON in the RUN key position.
4: The coil being used has the correct resistance in the primary winding's.
5: The resistance wire is doing it job correctly, lowering the coil voltage.
6: The ground side of the coil wiring is good.

If you need anymore information, regarding 1-6 above, free free to ask.
I did try to keep the above 1-6 as short as possible so I wouldn't be "pointing out the obvious".

Am I keeping up? I am trying to keep up, let me know.

Jim

 

No you are not keeping up.

1. NO WHERE Was it stated that the coil was hooked up when this test was done. What was said "in run position it has 7.45 volts at coil ,in start it has 12" Was the connector on or not ?

2. Obviously or it would not run in when the key was in start...

3. No it is being powered in the start potion the OP has NOT been clear on what wires he is reading from as the Harness is opposite from the ICM he has NOT specified weather he reading from the hanress side or the ICM side.

4. NOWHERE was this stated, try again.

5 Do you know for sure ? Have the ballast resistor been metered out for proper resistance? Possibly but again not really confirmed how it was done.

6 Is it really ? All that has been confirmed is there is continuity between the coil ground and the module when the system has a full 12V on the coil. What was the resistance on the system ground ? Oh wait no one knows as it HAS NOT BEEN CHECKED

I spend a lot of time in the improvement on these systems when I worked with Ford of Canada in the engineering Dept in the 70's and 80's. So I think I may just have a clue on how they work and just maybe might know how to diagnose them.

I have already said you have not added any value and was just making things complicated, apparently, that was NOT a subtle enough of a hint. So how is this, do yourself a favour sit back clam up, and you may just actually learn something

 

1: The OP did not state if the coil connector was off or on. But if it had been OFF it would had had 12 volt in both run and start, I thought this would have been obvious with your high degree of knowledge.
2: Fair enough, but it is still information gained from a single voltage reading so I added it to the list.
3: You are just total wrong on this one, I can't even throw you a bone. The 7.45 volt reading in RUN indicates current flow which can only happen if the DS2 module is power ON. If ... while reading 7.45 volts on the coil, you unplug the DS2 power connector the voltage reading will jump to 12 volts. Again... I thought this would have been obvious with your high degree of knowledge.
4: The DS2 module was passing current, so it was power ON in the RUN position. I and sorry this is something you don't understand.
5: The info was given in post 16, you replied in post 17. Also you can tell by the 7.45 voltage reading.
6: Sorry, but you are missing the big picture on this one. 4.55 volts are being dropped across the coil + the DS2 module + the negitive side wiring. This is a normal voltage drop. But to be fair The OP can repeat the test, getting voltage reading on both sides of the coil, so then we will know what the voltage drop is downstream of the coil. But it runs in START so it is an unlike to see an issue here.

Overall, I don't think you have a good understanding of the circuit. Something as simple as... current flow through a resistor causes a voltage drop... seems hard for you to understand.

I have read a lot of your posts and I think you have a lot of knowledge. It would be helpful if you could share it without sharing your attitude.

Jim