Base timing on Thunderbolt V ignition.

[njmorrell]

I have twin Mercruiser 454s with Thunderbolt V ignition.<br /><br />On one engine when I ground the purple/white wire it does not lock into base timing. Are there any simple tests with a multi-meter I can do on the ignition module?<br /><br />I have checked the voltage on the purple/white wire when not grounded, it is about 8.5V.<br /><br />Rgds Nick

 

[johnkc]

Re: Base timing on Thunderbolt V ignition.

do a continuity test on the purple white wire to make sure the wire isn't broken somewhere before the module.if the wire is good the problem must be the module itself.

 

[Trent]

Re: Base timing on Thunderbolt V ignition.

Just making shure. You did connect the jumper wire BEFORE the ign switch was turned on? If not it will not go into base timing mode.

 

[njmorrell]

Re: Base timing on Thunderbolt V ignition.

Thanks for the replies. In fact I took all the connectors apart and cleaned everything and now it works, I guess it was a loose or dirty connection.<br /><br />Also it doesn't seem to matter about grounding the purple/white wire before turning on the ignition. With the engine at idle 700rpm, with a timing light I see the timing varying between 8 and about 14 degrees BTDC, then as soon as I ground the wire it locks onto to 8 BTDC and does not vary.<br /><br />Rgds Nick