Ignition Woes at the Last Mile

[jimk]

From the many 123 fumbles, I understood that the 123 runs off +12 v all the time, start and run.  So no ballast resistor, no resistor wire, just 12v from ignition.

[John76]

Here's another way to test the ignition without the ignition switch...just to rule it out.

 

 

[0257]

Going through yesterday’s suggestions.  Initial observation: I get continuity from coil negative to diagnostic port 9, which runs through the tach. That suggests the tach’s not the issue.  But I’m not getting continuity from coil negative to ground, except when cranking, and I never get positive voltage through the coil, even though it tests good.  Question: should I get continuity from coil negative terminal to ground with switch off/accessory/run?

[John76]

No ... the only time you get continuity to ground from the coil (-) is when the "switch" (e.g. points or electronic module) is closed.

This only happens 4 times during every 2 engine revolutions. This charges the coil, and the spark happens when the "switch" is opened.

Easy to check when you have points. Your 123 dizzy might have instructions on how to check static timing using a 12v bulb.

[tzei]

Battery voltage when starting?

[2002iii]

I think it's the ignition switch. It's what sends voltage from the fuse box to the coil. 

 

I've had similar issues before. The last one I had shorted out internally when the metal detent ball got loose. The ignition switch started smoking. Luckily I had a battery kill switch.

 

The other issue I had was leaving the ignition in the run position after the engine cut our. The coil got so hot it started spewing its oil out of the top.

 

The design of the electrical system on 02’s is not very good. Full battery voltage is sent through the ignition switch putting a lot of stress on them.

 

I would recommend trying to remove your ignition switch. Sometimes you can just clean them up with electrical connector cleaner, but not while the battery is hooked up. 

[0257]

14 hours ago, John76 said:

Here's another way to test the ignition without the ignition switch...just to rule it out.

 

 

Car cranks just fine when I use my button start in this config. But no spark.

[ray_]

9 minutes ago, 0257 said:

Car cranks just fine when I use my button start in this config. But no spark.

With the key on?

[Son of Marty]

29 minutes ago, 2002iii said:

I think it's the ignition switch. It's what sends voltage from the fuse box to the coil.

I think that the switch doesn't provide power in the starting/cranking mode, it leaves that to the resistor bypass circuit which is missing on this car. Of course I might be wrong.

Edited January 22 by Son of Marty

[John76]

22 minutes ago, 0257 said:

Car cranks just fine when I use my button start in this config. But no spark.

Do you have continuity from the diagnostic pin #2 to the coil (+)?

Are all the Green wires connected to post(s) #15 on the ignition switch.

Something is very wrong ... and it's probably hiding in plain sight!

[0257]

1 hour ago, tzei said:

Battery voltage when starting?

Battery voltage is +12; when cranking drops to 10.5 or so. Starter cranks the motor very fast.

[0257]

35 minutes ago, ray_ said:

With the key on?

Both ways.

[0257]

1 hour ago, tzei said:

Battery voltage when starting?

12.5 sitting. Drops to 10.5 cranking but motor spins very fast.

 

I did do DLacey’s test 1 and can confirm coil is getting power and it throws spark.  I just did his test 2 and am starting to worry about the 123, as it’s not showing any voltage on cranking when my voltmeter is wired between ground and battery (using voltohmmeter instead of light bulb).  Need to check my test technique a few more times, but this matches impressions from previous testing over the weekend. The below is 123’s schematic for testing the dizzy, and I think I have duplicated it faithfully too.

 

Diagnostic pin 2 has continuity with coil pos.  I have not unbuttoned the dash yet bc I have done that too many times only to find the ignition switch is fine and it seems to be doing everything else it should.  I get that our ignitions are pretty caveman, but I have left the key on run for over 20 minutes sometimes  and my coil doesn’t even get warm.

 

Yes, the answer is hiding in plain sight.  Keeping one eye on the dizzy while I keep testing.

 

 

 

 

[John76]

11 minutes ago, 0257 said:

Battery voltage is +12; when cranking drops to 10.5 or so. Starter cranks the motor very fast.

Normal

11 minutes ago, 0257 said:

Both ways.

Normal.  Button start between #1 and #7 pins on diagnostic port spins the starter independent of the ignition switch.

What you need to confirm is +12V to coil (+) when #1 and #2 pins are connected.

[2002iii]

Did you get the upgraded distributor shaft?

 

If not I'll bet oil has fried the electronics inside the 123.