need help...Bill, Javier, Shogun, Winfred,...etc.

[HDhandyman]

I posted a thread a couple of days ago, and said I would post update, but the problem has not been resolved.

The car is at the indy.

Problem is diagnosed as "batter light intermitently not coming on, alternator then not charging battery"

So far, the alternator has been replaced 7-8 months ago, battery has been replaced (these 2 are not the problem). Unloader relay has been replaced. Grounds and straps are flawless.

Ok, so apparently there are times when I start the car, the battery light does not come on and go off, and then I loose voltage due to not charging, and begin to throw error messages (trans program, ABS, check engine) untill I am on the side of the road, or limping home. The problem is not easy to duplicate. Seems odd to me that the battery light in the dash cluster could cause so much problem, but I'm at a loss in terms of asessment. I know less than my indy who is very well respected and having enough trouble diagnosing this on his own.

Why is this only happening from time to time? Is it possible that the ignition switch has a short or something that occasionaly casues faulty start-up issues with the dash cluster battery light?---that's just a shot in the dark, but since everything else is clean, I'm looking for "domino" type ideas.

Any thoughts guys?

P.S. the car is still in the shop

[winfred]

id pull the brush pack off the alternator and check it just incase, i've seen them self destruct (had them crumble on a few month old bosch reman's), if that's not it check the small terminal on the alternator for power when it's not charging, no juice at the small wire no charge

[shogun]

Still thinking about a half broken wire or something like that, which in exceptional cases has no contact.
But I leave that up to the electric experts.
I only know that last year I had a similar symptom. It started that the aircon suddenly switched on or off, blower fan did not stop, sometimes funny info on the check control and so on, finally it turned out that 2 cables in the engine main harness got lose over the time, sometimes they still worked, somtimes not, till the car finally broke down and was in limpmode.
That was at least good, as it is easier to check for a permanent fault than for one which comes and goes.

[HDhandyman]

Still thinking about a half broken wire or something like that, which in exceptional cases has no contact.
But I leave that up to the electric experts.
I only know that last year I had a similar symptom. It started that the aircon suddenly switched on or off, blower fan did not stop, sometimes funny info on the check control and so on, finally it turned out that 2 cables in the engine main harness got lose over the time, sometimes they still worked, somtimes not, till the car finally broke down and was in limpmode.
That was at least good, as it is easier to check for a permanent fault than for one which comes and goes.

that's interesting, because from time to time when I'm running the A/C, the car will occasionally power down almost completely and struggle to do 20 miler per hour. This just occurs for a few seconds then power comes back to full strength. This was happening more and more frequently right before this "new" problem occured. Can you be more specific about the cables in the engine main harness? I assume they where in a seven. Do you know what the equivalent cables are in my 525?

[shogun]

It was in the main engine wire loom. That means the cables which go from the engine to the MOTRONICs (in my case 2 on the 750) and EML (the 750 has 1) and to the X20 and X21 terminals and from there to the diagnosis box. X20 sits just besides the diagnosis box and X21 next to it towards the window.
In your case there is probably only one box next to the diagnosis box.
Here is a pic of the 750 engine room, it is on driver's side, the 3 round plastic boxes where all the cables go in
http://www.gebrauchtee32teile.de/ass...lder23_052.jpg
http://www.gebrauchtee32teile.de/ass...lder23_071.jpg

In the end I even could not read the cluster anymore, car was in limpmode, and other things. Even could not read anymore the PEAKE, it just said 'error'.
The cables are fed from the bottom into the sockets and parranetly by vibrations over the years the hooks on the contact pins got lose and they slipped down.
Usually an electrician can meaure all the cables, should be no problem for him if he has a wiring diagram.
Wiring diagrams are on bimmerboard under related links to the right on top
http://www.bimmerboard.com/forums/e34/
under electronics, they are called electronic troubleshooting manual. Study that in detail, because on one page there is exactly shown where the wires are connected in the engine room, it says the name of the connector and so on.

[HDhandyman]

I forwarded this thread to my mechanic. He thought the ideas of Winfred and Shogun were both very good. He was especially intrigued by Shogun's response about the main engine wire loom, and decided to investigate. Unfortunately, all the wire lengths are spec, and everything checks out. So, I think that he has pretty much decided that the problem exists within the dash cluster....just through process of elimination.

Thanks to all for the ideas and support. If there are any other ideas, I'd love to hear them.

I brought the car home yesterday because we are unable to duplicate the problem, and I might as well drive it untill this occurs again.

[Ross]

I don't agree with the cluster theory as the only part of this system in there is the bulb and this car does not use the bulb to complete a circuit.
The brush idea sounds good except I can't imagine that being intermittant.
My thought is the switch as you guessed. This is some thing that could cause what you have described. I would bet on it.
According to my diagram it's the green wire that supplies the unloader relay and the light.

[winfred]

seen it a few times where it will charge just enough to keep the car starting daily but as you drive it runs outta power and dies, manual tranny cars can get weird where it will die going down the road and refire before the engine stops spinning

The brush idea sounds good except I can't imagine that being intermittant.

[SnakeyesTx]

Not sure if this has been thought of or voiced yet, but I've had this happen several times myself (on other vehicles).

I'll use my J-20 as an example (Jeep... monster.. heavy... huge... 1 1/2 ton modded)

I replaced everything on it, and since I was running tons of lights and power hungry accessories, I decided to go with a Zero gauge battery cable for both + and -. They worked fantastic for about 3 years, and the insulating cover of the wire always looked fresh, soft, pliable like the day I bought them.

One day I drove to work, and when I was about to head home, -click- won't start. Got a jump, voltage gauge was pretty low, but the ammeter was flickering from charge to discharge almost the whole way home. Thought maybe the diode trio in the alternator was bad, checked ok. Lifetime warranty, got it swapped out anyway just for peace of mind and I bought a new battery to boot.

Next day, drove to work, wouldn't start again when I got off. I was pretty puzzled for a few days when my neighbor came over and cut the covering of my + cable, and lo and behold the wire inside was covered in white and green corrosion and powder.

Your issue could be very similar regardless of the outside appearance and causing an inconsistant connection for charging/discharging giving you this nightmare you're going through.

On a side note, I was about to make a thread asking if anyone has gone through the nightmare of changing their + cable from the backseat thru the body up to the front. I can't even imagine what kinda chore that's gonna be when mine bites the dust.

[HDhandyman]

Not sure if this has been thought of or voiced yet, but I've had this happen several times myself (on other vehicles).

I'll use my J-20 as an example (Jeep... monster.. heavy... huge... 1 1/2 ton modded)

I replaced everything on it, and since I was running tons of lights and power hungry accessories, I decided to go with a Zero gauge battery cable for both + and -. They worked fantastic for about 3 years, and the insulating cover of the wire always looked fresh, soft, pliable like the day I bought them.

One day I drove to work, and when I was about to head home, -click- won't start. Got a jump, voltage gauge was pretty low, but the ammeter was flickering from charge to discharge almost the whole way home. Thought maybe the diode trio in the alternator was bad, checked ok. Lifetime warranty, got it swapped out anyway just for peace of mind and I bought a new battery to boot.

Next day, drove to work, wouldn't start again when I got off. I was pretty puzzled for a few days when my neighbor came over and cut the covering of my + cable, and lo and behold the wire inside was covered in white and green corrosion and powder.

Your issue could be very similar regardless of the outside appearance and causing an inconsistant connection for charging/discharging giving you this nightmare you're going through.

On a side note, I was about to make a thread asking if anyone has gone through the nightmare of changing their + cable from the backseat thru the body up to the front. I can't even imagine what kinda chore that's gonna be when mine bites the dust.

Damn, that's a good idea! *grabs RJ 11 wire strippers*