Battery light coming on. Battery voltage PID at 13.6v

[olopezm]

Hello guys, haven't posted here in some time.

This time I'm in need of help as I'm running out of ideas on this matter.

SYMPTOMS:

1- Battery light started to come on intermittently. There is no pattern for it to happen, it can be while the engine is hot, cold, at idle, under load, no electrical load or heavy electrical load.

I decided to drive around with my EZ-SCAN 6000 connected and monitored the battery voltage PID all the time; I triggered the scanner as soon as the light came on to see if there was any variation. Voltage remained 13.6-13.8 volts at all times, even under heavy electrical load (headlights, fog lights, A/C compressor engaged, blower at max, rear defroster, radio on, 1000w amp and sufwoofer). I must say that even when it is a 1000w amp, I rarely crank the volume high enough to put a strain on the system.

I have a set of HID bulbs and ballasts, I thought those could be the problem as the light came on a few seconds after turning them on, and batter light would go out if I turned the headlights off. I pulled over to the side of the road to check with my multimeter and voltage on the alternator was fine (14.6v). This HASN'T happened again.

2- ABS and Parking brake light remained lit after starting the engine. These were also erratic, they would come on after cranking the engine, or not.

I cleaned the ground on the fender, by the battery, and i seemed to get rid of this problem. Also cleaned the terminals on the battery and the wire on top of the fuse box under the hood. Problem seemed to disappear.

3- Low coolant level also comes on when turning the key to the RUN position, if I leave it there, the light will slowly fade out. If I start the engine, it will stay lit for 3-5 seconds and go out. COOLANT LEVEL IS FINE.

4- ABS light started to come on after cranking the engine. It can also happen or not. 2 out of 3 times it will stay off.

THINGS DONE SO FAR:

- Cleaned battery terminals.
- Cleaned ground on passenger side fender, next to the battery.
- Cleaned fuses inside the cabin, terminals had some build up on them.
- Cleaned ground on the ICM bracket
- Cleaned positive cable on top of fuse box under the hood.
- Had the charging system tested at autozone. Battery, alternator and starter tests came out good.
- Checked grounds under the dashboard (one behind the fuses, one on the steering column) and they were fine.

Tomorrow I'm planning to check the ground on the transaxle stud.

As a side note, I replaced the ignition switch harness on february of this year because of the blower working only on high and DRL's going out (they are disabled anyway).

As I said above, I'm running out of ideas. What do you guys suggest?

Oscar.

[olopezm]

Today I cleaned the block main ground, close to the starter, on the transmission; it didn't look bad, but still gave it a good clean. Also took my time to clean the positive cable on the starter, the nut holding it was so loose that I removed it by hand...

While I was there, I cleaned every single fuse under the hood as they also had some carbon build up on the terminals.

While testing with the multimeter and my scanner, I realized that the battery voltage reading on the scanner can be from .5 to 1 volt below the actual voltage. I compared the multimeter's reading against the scanner's and DMM was higher; the more the electric load the bigger the difference between both readings.

So far it seemed OK as the coolant light didn't come on, nor the alt light did. We'll see...

Oscar.

[rickisrad]

Looks like you are going in the right direction. I would have supected a bad ground, corroded fuse box or a bare wire shorting out somewhere.

[olopezm]

Thanks Rick,

Yeah after having another look at the wiring diagrams, those cables on the starter must have been the actual culprits as the battery cable routes to it and both the alternator and power distribution box cables are also on the same lug. Since the nut was loose, the cables weren't making enough contact.

Since I focused on bad grounds, I didn't pay much attention to that part of the diagram and was hesitant that it would solve my problem; no I'm 99% sure it's solved for once and for all.

I'll update in either case.

Oscar.

[kevinande]

Are you sure 13.8 is enough? I would check that to sure. Every car I own puts out at least 14 volts while running. Check your accessory belt to and make sure it is nice and tight as well.

[olopezm]

I said in my post from yesterday that there is a .5 to 1 volt difference between the battery voltage PID and actual voltage at the battery seen with a multimeter, and that the heavier the electrical load, the bigger the difference will be. That leaves us with 14.3 under regular load and 14.8 or more under heavy load.

A voltage drop test showed .6 volts between the lug on the alternator and the terminal on the battery. I cleaned all terminals so it must be internal wire corrosion that's causing it.

Oscar.

[aleekat]

A voltage drop test showed .6 volts between the lug on the alternator and the terminal on the battery. I cleaned all terminals so it must be internal wire corrosion that's causing it.
.6 is probably close to max allowed. I would replace the cables.

[olopezm]

Yes, I will likely do that but some day, it currently doesn't bothers the fact that there is a drop in voltage as long as it doesn't starts creating bigger problems. With the prices dealers have around here, it's almost forbidden to think of it as a resource; a few years ago they wanted $1278 for a new rack and pinion, yes, just the part, no labor!

I drove the car today and so far everything seems OK. No weird lights nor intermittent cranking. Looks like it's solved for once and for all!

Oscar.

[rickisrad]

The dealer is ridiculous with any part. Parts stores have the rack for under $200.