Diagnosis challenge: why does ABS light lead to battery charging problem?

[Thawley]

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Looking to see if this is a common/easy issue before I call in the cavalry...

Yesterday: noticed that the ABS light was on. "That's odd" I thought. So I shut it down when I got home. Then restarted it – still get the light. "Hmmmm, wonder what that's all about?" Go in, have dinner, forget all about it.

Today: "click" – battery dead, no stratum.

Then: charge the battery for a few hours. Start it up – let idle if 20 min. Perform safety check before I leave to get stranded somewhere – turn it off to try a restart. "Click"

So – I've got no charge light and no CEL. But I DO have an ABS light and apparently no charging. Batteries are about 18mos old.

Any guesses?

Datum: 2004 Excursion 6.0, 2wd, replaced both engine harnesses 2 years ago and has been 100% trouble-free ever since.


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[m-chan68]

Straight from the Ford Workshop Manual, Section 206-09, Pinpoint Test 'Q' for DTC B1676 Voltage Out Of Range. This pinpoint test instructs you to check the voltage reading across pin 16 (tan w/red tracer) and pin 8 (light green w/yellow tracer) of the main ABS connector (with the connector disconnected from the module and the engine running). It then asks if voltage is greater than 16.6 volts or less than 9.2 volts. If YES, the next step is to CHECK CHARGING SYSTEM. If it does fall between the above readings, it instructs you to replace the ABS module. If I were to guess, I would say it has to be less than the latter of the two voltages specified, by what you are describing.