Bosch 160 Amp alternator

[Fless]

Yes. The snap on Zeus is not your average scanner. As I understand its a $10k plus device.

Sam I took your advice disconnected and cleaned out my ECM connections. There was some dark oil crap on them! Probably oil from gearbox?? It was on the lower end of both connectors. Hit it with some electrical contact cleaner and blew both out with compressor air. Seeing a solid 14.8 on voltmeter while truck is idling. Going to drive it all day and keep eye on gauge for drops

Might be time to think about replacing the ECM connection gaskets.

 

[Fless]

Check out this Service Bulletin (attached). Excerpt:

 

[blueinkd]

Well. I have never seen the voltage below 14 as long as I have had the truck now. That bulletin is interesting.

I also have already installed a NEW alternator from AZ and took it for a 30 min drive. Voltage was right at 14 on gauge and multimeter showed a steady 14.6-14.7 at idle.

Also when I reconnected my negative with new alternator installed there was no spark like before with old alternator. I had disconnected negative cable several times when I removed starter, took battery for a recharge, etc. Something internally wrong with old alternator maybe.

 

[wildcatgoal]

Battery drain testing should yield (once all latent electronics turn off) no more than .05 amps. That or less and you're fine.

I would also caution on leaning toward a new alternator. I went through two Remy 145 amp alternators in the past few weeks. Both whined like crazy out of the box and both charged at 14.9-15.1 volts (not necessary, not good). Returned them, got an AC Delco 130a rebuild... dead quiet and it charges at 14.4-14.8 volts like a standard alternator should. I realize the Bosch units are different, but a good reman done in Mexico turned out to be better than two new alternators made in who knows where. And it has a 2-year warranty... if it breaks after 2-years, darn.

 

[wildcatgoal]

Also when I reconnected my negative with new alternator installed there was no spark like before with old alternator.

View attachment 273942

A lack of spark reconnecting a negative terminal is not indicative of much, if anything. The spark tends to come from a sudden draw of power to charge capacitors throughout the car's electrical system.

 

[blueinkd]

Truck has been driving fine since alternator install. Looks like it was intermittently charging.

 

[2006Tahoe2WD]

Are you sure that the drain that was measured was .05 to .08 ma? Sure you don't mean that was in amps? (would be 50 to 80 ma)

On my '04 I have the automatic HVAC control, and the spec for that to go to sleep is a bit over 4 hours. Draws probably 60-some ma until it sleeps. Mine takes about 3.5 hrs. to go night-night, then it's down to about 30ma total draw.

And does your truck have the variable voltage sensor that adjusts the charge voltage? I forget what they call that....

You bring up a very good point. After a certain year (2003?) the charging system is adaptive. In order to improve battery life the system attempts to guess the temperature and charge state of the battery. When all is good the volts may drop to 13 and other times be higher. It's not like the "old" systems where we expect the volts to be e.g. a steady 14.2 at all time. I also read that when the head lights are on the system keeps the volts high.

 

[Fless]

You bring up a very good point. After a certain year (2003?) the charging system is adaptive. In order to improve battery life the system attempts to guess the temperature and charge state of the battery. When all is good the volts may drop to 13 and other times be higher. It's not like the "old" systems where we expect the volts to be e.g. a steady 14.2 at all time. I also read that when the head lights are on the system keeps the volts high.

Believe adaptive charging came in 2005. Definitely not in 2004 for my stock Hoe.

 

[2006Tahoe2WD]

okay - 2005. My 2006 Tahoe - new battery and rebuilt alternator is now often charging 14.9. I'll see how it goes - should kick down a bit at some point.

 

[2006Tahoe2WD]

I thought I should post because it seems I found the cause of high charge voltage. It was the new battery. I got time to go have it tested and the tester said low cranking amps. Something was wrong with that new battery. The store gave me another new battery and it seems to have fixed the issue. I can see the adaptive system charge the battery after starting and then reduce the volts to around 13. No more 15.2 volts while driving for long periods.