1969 Engine Wiring Harness Replacement - will not fire

[Peter S.]

All,

I replaced my engine wiring harness in my 1969 L46 w/ TI. The unit came from Lectric Limited, and I purchased the appropriate connector from Paragon to replace the ignition coil terminal to connect to the TI system.

As all projects take me forever, the car sat for a while. Before starting I pulled the distributor (appropriately marked) and primed the motor w/ fresh oil.

The starter turns the motor over perfectly, but I'm not getting ignition. Every few seconds or so I get small puffs out the tailpipe.

I've double checked all connections, specifically focused on the ignition coil to distributor and the wire modifications to harness for TI.

I'm clearly overlooking something. Seems as if I'm getting weak-to-no spark, which is leading me back to the coil (207).

This motor ran perfectly before replacement.

[Harry S.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

All,

I replaced my engine wiring harness in my 1969 L46 w/ TI. The unit came from Lectric Limited, and I purchased the appropriate connector from Paragon to replace the ignition coil terminal to connect to the TI system.

As all projects take me forever, the car sat for a while. Before starting I pulled the distributor (appropriately marked) and primed the motor w/ fresh oil.

The starter turns the motor over perfectly, but I'm not getting ignition. Every few seconds or so I get small puffs out the tailpipe.

I've double checked all connections, specifically focused on the ignition coil to distributor and the wire modifications to harness for TI.

I'm clearly overlooking something. Seems as if I'm getting weak-to-no spark, which is leading me back to the coil (207).

This motor ran perfectly before replacement.

Peter, I have a friend with the exact same problem. Simple fix, he forgot to install the rotor. Double check everything.

[Richard M.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Peter,

Since you had the distributor out did you verify all wires are configured properly? Rotor Back in, etc? If so a few other things to check.....

Connector plug at TI Module properly seated?

TI Module has a clean ground to the Radiator Support? Verify with ohm meter to engine ground.

Ign Coil Neg terminal properly Grounded? Verify with ohm meter to engine ground.

TI is very sensitive to proper voltage during crank. The Solenoid R terminal yellow wire should be connected to the pink in the plug at the distributor and during Crank ensure there is sufficient battery voltage there using a voltmeter.

66-71_Diagram.jpg

Also attached is the 66-71 diagnosis chart below.

Do some of these tests and post back with results.

Rich
PS Edit Add.... I made these up a while ago when someone was rewiring their TI. It may help.
1969_K66_A3_Crop1.jpg

1969_K66_A3_Crop2.jpg

[Floyd B.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Peter,

At some point during its sorry existence, my '69 big block had the special white/red-stripe resistance wire between the ignition switch and coil replaced with an external balance resistor, which had been mounted to the firewall with a drywall screw. When I replaced the engine harness, I had to get rid of the external balance resistor (and the drywall screw). The coil had also been replaced. Are you sure the harness replacement hasn't created a resistance mismatch? Is your coil a B-R or non-B-R?

-Floyd-

[Peter S.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Peter,

At some point during its sorry existence, my '69 big block had the special white/red-stripe resistance wire between the ignition switch and coil replaced with an external balance resistor, which had been mounted to the firewall with a drywall screw. When I replaced the engine harness, I had to get rid of the external balance resistor (and the drywall screw). The coil had also been replaced. Are you sure the harness replacement hasn't created a resistance mismatch? Is your coil a B-R or non-B-R?

-Floyd-

Hi Floyd - the new harness matched up very well with the unit in the car, with exception to the TI connection, which another member pointed me towards the modification to the harness. When it comes to wiring, the word "novice" couldn't describe my abilities any better. But, the wiring match up between old and new makes me feel comfortable with the replacement. I have had zero issues with the 207 coil prior to the harness switchout, which is a service replacement TI coil.

[Peter S.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Hi Richard - I'm trying to work through this slowly as this is far from my forte. Regarding the TI module - I'm operating on the assumption that since nothing was touched on or near the module that there should be no affect here. I struggle to even see the module, let alone reach it and verify connections.

Same with the coil - I haven't touched the coil directly, so grounding should be unaffected. But, I can investigate this further if we can rule out my connectivity at the harness.

TI is very sensitive to proper voltage during crank. The Solenoid R terminal yellow wire should be connected to the pink in the plug at the distributor and during Crank ensure there is sufficient battery voltage there using a voltmeter.

I think this could be where I'm amiss. The R-terminal yellow wire is connected to the pink wire in the plug at the distributor w/ the modification I made. How can I ensure there is sufficient battery voltage here? What should my voltage be (~12.5 min?) and how might I measure this exactly w/ a multimeter? EDIT: with the ignition switch on, I'm only measuring 2.7 VDC across the coil (battery down to 12.5 VDC).

[Peter S.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

EDIT: Richard, just saw you posted this in your initial reply. Thank you, very handy.

I found this document. Based on this, if I'm measuring 2.5 volts, it's pointing me towards a distributor issue.

I properly marked the distributor when I pulled it for priming. I'm curious where I could have gone wrong in this regard.

TI Ignition Diagnosis.jpg

[Richard M.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Peter,

The module connections could cause issues, as well as the grounds, so I just wanted to add those to the list as possibilities. Sometimes while working in the engine bay things can get disturbed.

As far as Crank voltage at the Yellow wire, using a voltmeter, this is what I do....

A helper is at the Key switch.

Connect your meter pos+ to the Bat+ post. Meter neg- to Bat- post.
Helper crank the engine, record the reading.

Then....

In the engine bay, connect the meter pos+ to the Yellow wire(or best, the Pink wire in the distributor plug). Meter neg- to Bat- or clean engine ground.
Helper crank the engine, record the reading.

Both readings should be very similar, within about 0.2v.

If during Crank the voltage at Yellow/Pink is less than 12 volts it could result in a no-start, i.e. not enough voltage to trigger the TI module/Pickup Coil. If the Solenoid R function isn't there, the TI and Pickup Coil is only getting it's voltage from the Ignition switch, which may not be enough even with a fully charged battery.

Also, TI does not act like points ignition at the Ign Coil. Voltage to the Ign Coil comes from the TI Module as it does the switching. Note in the Diagnosis chart, that with Ign ON, 2.7V is within spec(2.5v-4.5v).

12.5V at the battery at rest is a tad low so you may want to put a charger on it for a while too.

Rich

[Peter S.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Another observation - with the ignition in the on position, when I touch the modified yellow R wire that's connected to the TI pink wire, there are audible spark/popping sounds within the distributor.

[Richard M.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

EDIT: Richard, just saw you posted this in your initial reply. Thank you, very handy.

I found this document. Based on this, if I'm measuring 2.5 volts, it's pointing me towards a distributor issue.

I properly marked the distributor when I pulled it for priming. I'm curious where I could have gone wrong in this regard.

Yes, but you still want to verify that yellow/pink wire circuit voltages, as I explained in the previous post just as you replied.

Also as the chart suggests, if 2.5-4.5 ON, unplug the distributor plug and put a ohm meter across the distributor terminals. 500-700 ohms typical, but..... if you have a helper while measuring, wiggle the wire pair going up into the distributor base to make sure its not intermittent. Common problem with those wires.

Just for my info, is your TI module original or is it a new replacement internal circuit board, and if so, do you know which manufacturer?

Rich

[Richard M.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Another observation - with the ignition in the on position, when I touch the modified yellow R wire that's connected to the TI pink wire, there are audible spark/popping sounds within the distributor.

That may be a intermittent connection at that plug/wire-pair I just described. Hopefully not a short in there somewhere.

Best to Shut down and do that ohms test of the distributor plug mentioned.

Rich

[Peter S.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Peter,

The module connections could cause issues, as well as the grounds, so I just wanted to add those to the list as possibilities. Sometimes while working in the engine bay things can get disturbed.

As far as Crank voltage at the Yellow wire, using a voltmeter, this is what I do....

A helper is at the Key switch.

Connect your meter pos+ to the Bat+ post. Meter neg- to Bat- post.
Helper crank the engine, record the reading.

Then....

In the engine bay, connect the meter pos+ to the Yellow wire(or best, the Pink wire in the distributor plug). Meter neg- to Bat- or clean engine ground.
Helper crank the engine, record the reading.

Both readings should be very similar, within about 0.2v.

If during Crank the voltage at Yellow/Pink is less than 12 volts it could result in a no-start, i.e. not enough voltage to trigger the TI module/Pickup Coil. If the Solenoid R function isn't there, the TI and Pickup Coil is only getting it's voltage from the Ignition switch, which may not be enough even with a fully charged battery.

Also, TI does not act like points ignition at the Ign Coil. Voltage to the Ign Coil comes from the TI Module as it does the switching. Note in the Diagnosis chart, that with Ign ON, 2.7V is within spec(2.5v-4.5v).

12.5V at the battery at rest is a tad low so you may want to put a charger on it for a while too.

Rich

Voltage at battery when cranking: 10.7 V.

Putting the meter + within the backside of the yellow/pink wire connector and meter - to the negative post of the coil, I read 8.6 V.

Battery is now on charger.

[Richard M.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Voltage at battery when cranking: 10.7 V.

Putting the meter + within the backside of the yellow/pink wire connector and meter - to the negative post of the coil, I read 8.6 V.

Battery is now on charger.

Peter,

Yes, the reading on the battery is way too low for TI. And that 8.6v on the yellow is telling me you're not getting Bat+ voltage during crank. Should have been 10.6 or so, so you have a 2 volt drop, and is likely what you get from Ign switch only. Regardless, battery needs a charge for sure.

While the battery is charging(disconnected from the car), you should check your yellow connection down at the Solenoid too. Maybe even do a ohms test for continuity of the Yellow terminal from down there up to the connector. It appears it's open somewhere, or a bad solenoid. Make sure the Yellow terminal at the solenoid R is tight.

After battery is charged up you may want to do the same (step 2)Crank tests, this time at the Solenoid R terminal itself. If you can get under there, best to connect a jumper wire accessible up in the engine bay for safety so you're not under it during helper crank. Compare Step 1 to Step 2 again.

My gut feeling is you have a low/marginal battery and maybe a intermittent solenoid issue. Although with only 10.7v at Crank, the solenoid may not be getting the best drive to make a good contact.

Rich

[Peter S.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Hi Richard,

I've cleaned the R terminal and reconnected (very snug) the yellow wire. How do I do the ohms test here?

This was a brand spanking new battery after the engine harness install, I have certainly worn it down after all the crank attempts. Hopefully it'll be ready here shortly for round two. A few question from above:

Also as the chart suggests, if 2.5-4.5 ON, unplug the distributor plug and put a ohm meter across the distributor terminals. 500-700 ohms typical, but..... if you have a helper while measuring, wiggle the wire pair going up into the distributor base to make sure its not intermittent. Common problem with those wires.

I've disconnected the white/green + white distributor plug from the connector with the two pinks + gray wire plug. Connecting my meter to the white/green + white terminals in the distributor, I measure 583 ohms.

[Richard M.]

Re: 1969 Engine Wiring Harness Replacement - will not fire

Hi Richard,

I've cleaned the R terminal and reconnected (very snug) the yellow wire. How do I do the ohms test here?

This was a brand spanking new battery after the engine harness install, I have certainly worn it down after all the crank attempts. Hopefully it'll be ready here shortly for round two. A few question from above:



I've disconnected the white/green + white distributor plug from the connector with the two pinks + gray wire plug. Connecting my meter to the white/green + white terminals in the distributor, I measure 583 ohms.

Peter, Good work....

Battery may have been ok but with the cranking lost it's energy. Because of this I'm more suspicious of the Yellow circuit during Crank. If it was bad, it'd cause what's going on.

To do the ohms test for the Yellow, just do a ohms test between the Solenoid R stud up to the Yellow/Pink connector in the engine bay. This just checks if the wire is good. Never know, a new harness could be defective.

And 583 ohms is ok for the PU coil. But also best to wiggle the wires under the distributor to be sure it's constant. Also I forgot but a good idea to ohm test each wire to ground too. If ~0 ohms, PU is shorted to ground.

Rich