Bosch 160 Amp alternator

[blueinkd]

2005 Tahoe. Been chasing intermittent battery drain issue last two weeks. My girlfriend has been driving my truck. Todsy it was hooked up to my friends Snap On Zeus with his amp meter tester. We measured a drain of .05-.08 Milliamps across 4-5 hours of observation. Going home I noticed the battery gauge below 14 volts got home and multimeter read 12.5-13.5 at idle. Never went above 14 volts. So I'm leaning towards bad alternator. Might go back to my buddies house tomorrow to see what he can check with his scanner.
Question is: What is the difference on the Bosh 160 alternator besides the obvious case? I'm trying to buy a replacement one tomorrow from Autozone but don't want Reman.

The new one looks like this but notes indicate it's for Bosch equipped trucks.

https://www.autozone.com/batteries-...t-gold-new-alternator-dlg2207-16-2/224305_0_0

 

[Fless]

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....

 

[blueinkd]

The snap on scanner measured 0.05-0.08 milliamps through the entire 3-4 hours we watched it. It took less then 10-15 mins for it to reach this. I do have the auto Temps but don't like to use it, I normally set the temp where I want it. I do believe the 05s have the computer regulated alternator function.

 

[Fless]

It doesn't matter if you use the HVAC control or not, at least on mine. It wakes up on most drive cycles and stays awake for a while after shutting down the truck.

Is this SnapOn scanner measuring the overall draw inductively, or is it connected inline with the negative battery cable? It's very difficult to accurately measure ma unless using direct connection or a shunt. The ma numbers you are stating are suspect; not many meters read that low. And if they're correct they're nothing to be concerned about. Generally a 50ma or less draw while asleep is good.

I would suggest using one of many available test procedures to isolate the circuit that is giving you problems. Eric O at South Main Auto on YouTube has several videos about parasitic drain, how to measure drain across a fuse without pulling the fuse, etc. If you need more direction finding those resources let us know. Search for "parasitic" here on TYF, too.

A few wild guesses:

Have the battery load tested.

Leaving the radio on when shutting down the truck (allowing RAP to keep it on), does it shut off when you open any door? It should. The interior lights should also fade out within a minute after closing the door. If they don't, suspect the driver's door latch.

Also on a whim, you might gently disconnect your PCM connectors from the PCM and inspect them for corrosion or water intrusion.

 

[blueinkd]

He had some probe connected around the negative battery cable and that was exactly what the snap on reader was seeing. We tried several things. Drove it parked it, blasted radio for 30 mins and turned it off, let it idle in his driveway and turned it off. All results lead to those readings after 15-20 mins of being off and scanner reading.

My main question for this thread was the alternator appearance. Mine looks like the rebuilt unit from AZ. I want a new one so I have the Gold NEW unit in the garage which has same plug for regulator but different case. It's notes say for Bosch 160 amp . Any comments on using the new unit?

 

[Joseph Garcia]

Agree with above. Must be a sophisticated multimeter to read .05-.08ma. That is a very small amount of current, and IMO, you could leave that draw on a truck battery for days, if not weeks, before the battery would be drained.

Other folks more familiar with the specific alternator details related to your question will chime in with their perspectives.

 

[blueinkd]

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

 

[Fless]

About the alternators, then, it looks to me like the connector clocking is different. One is on the back of the case and the other is on the side, at somewhat different clock positions relative to the main mounting ear. No idea if they're interchangeable.

 

[blueinkd]

Well. Alternator definitely still not charging. After 5 mins of driving gauge sitting below 14. Tested with voltmeter and barely at 12.6-13 at idle

 

[exp500]

Thats the computer controlling the voltage, At the alternator should be 12.7-13v min. output. Now another issue is an AZ reman may not follow the factory map for voltages, or a weak battery doesn't have the reserve capacity left. A battery load test is a good idea. No reason to run a 160 amp if you don't need it. (total Load).

 

[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.