95 SN OB GT-40 -- Grounded tach lead or switched B+?

[sherrema]

First time poster here - I hope I didn't miss a post that had my situation - I couldn't find it!

I have no spark.

I have the GT-40 service manual and I'm confused between two solutions:

1. Test 3F1-9: measuring between purple/black and ground gives me 5.1V, not exactly battery voltage! So I say no and go on.

2. 3F1-14: take 60-pin connector off ECA. Testing 12.3V between 37/57 and 20/40/60. So, yes. It says repair defective purple/black wire circuit between ECA and coil.

3. OK, but for fun I go back and do 3F1-9. I get 12.3V with the ECA disconnected. If I say yes to 3F1-9 it sends me to 3F1-10. My coil resistance is within spec on both circuits so I go on.

4. 3F1-11: I put my ohmmeter between the gray wire and ground. It's supposed to read infinity but I'm getting +/- 4700 ohms. So now it says repair grounded tachometer lead!

So, do I chase number 2 above or number 4 above? That wiring harness, with all the nice braided tubing, looks like a nightmare!!!

Any advice?

Thanks in advance.

[DanielC]

I would start witha little more basic tests. Do you have battery voltage at the coil?
Every ignition system I know of has to supply battery voltage to the coil, and the coil ground is switched on and off by a switch of some kind. There should be a way to disconnect the tachometer wire close to the distributor, so you can eliminate a grounded tach wire.

[sherrema]

Right, that's what I'm saying. I have 5.1V at the coil with the ECA connected and 12.3V with the ECA disconnected. Any more thoughts? Thanks,