I replaced my battery about 2 months ago. Then my battery light kept coming on during hard acceleration. Then the battery light stayed on no matter what. I knew I had to suck it up and replace the alternator, so I had it replaced with a new one.

So... everything has been fine for 8 days. However, today, while the truck is running, the ABS light comes on, followed by the battery light. Sometimes the battery light will come on and then the ABS light. I cannot seem to determine a pattern.

Here's the kicker... When this happens, the battery volt meter (one word?) shoots up to H (as high as it will go). The truck does not exhibit any other symptoms. The brakes are working fine and the ABS is NOT kicking in randomly. If it were slick outside, I would try to see if the ABS system is working, but it is not slick. The CEL is not on and does not come on.

Also, this is not happening constantly. It seems to happen under normal acceleration, while in 1st gear (although it may be happening at other times when I'm trying to watch the road haha).

After digging around posts, forums, and the internet, I see this has happened to other people after replacing the battery and alternator. So, I'm hoping this is just a sensor problem or some sort of short. However, none of the posts I have seen detail how to fix this.

I plan to see if AutoZone can read the ABS code(s). I'm thinking the battery voltage is out of range and thus the ABS is shutting off to prevent damage. All I have tried to do so far is disconnect the battery, but that has not helped.

Please let me know if I'm missing something, if there is a simple fix, if I'm doing something wrong, if the mechanic messed up while installing the alternator, etc. I'm also wondering if there could be a short in my amplifier (although no other posts have had this problem).

Truck Specs:
- 2003 F-150 w/ 115,000 miles
- 4.6L V-8
- 2 wheel drive
- Sport model w/ 3.55 gears
- Small amp (760 watts max, but probably using around 250 max) w/ 2 small subs

 

Small update:

- The red brake light does not come on.

- Many posts talk about replacing the ABS sensors either in the rear or on the front two wheels. However, this seems to fix the problem when the ABS light is constantly on and there is no mention of the battery light/gauge problem, so I'm thinking this is not a sensor. My ABS light is NOT CONSTANTLY on... I'm starting to think this is a battery or alternator problem since none of this was happening before those two were replaced.

I'm off to check fuses now...

 

Start with getting the new alternator load tested.

If the power is running up that high, that seems to be an out of bound high voltage limit, which by the DTM in the HEC ranges would be 16.9-19.1 volts, high voltage

If you check with the DTM in the HEC, it could verify this

Activating Test Mode

To enter the HEC Dealer test mode, depress and hold the instrument cluster SELECT/RESET button, turn the ignition switch to the RUN position, and then continue pressing the SELECT/RESET button (5 seconds) until tESt is displayed in the odometer. The SELECT/RESET button must be released within 3 seconds of the odometer tESt display to begin the dealer test mode.

Depress the SELECT/RESET button to advance through the following steps until dtc is displayed. Depressing the SELECT/RESET button will display any stored continuous DTCs before proceeding to the next step.

GAGE
Activates gauge sweep of all gauges, then displays present gauge values. Also carries out the checksum tests on ROM and EE. If the gauge sweep is inoperative, INSTALL a new instrument cluster.

All segments illuminated
lluminates all odometer segments. If any odometer segment is inoperative INSTALL a new instrument cluster.

bulb
lluminates all micro-controlled indicators and LEDs. Install a new indicator or LED as necessary.

r
eturns to normal operation of all micro-controlled indicators and LEDs and displays hexadecimal value for ROM level. (used when requesting assistance from the hotline). If alternating flashes for FAIL and ROM level are displayed, INSTALL a new instrument cluster.

EE
Displays the hexadecimal value for EE level (used when requesting assistance from hotline). If alternating flashes of FAIL and EE level are displayed replace instrument cluster.

dt
Displays hexadecimal coding of final manufacturing test date (used when requesting assistance from hotline).

dtc
Displays continuous DTC's in hexadecimal format. Pressing the SELECT/RESET button will display any DTCs stored before proceeding to the next step.

enG
Displays the English speed in MPH. Speedometer will indicate present speed within tolerances. Display will show 0 if input in not received. If input is invalid for one second or more, or if speed is 0.

m
Displays the metric speed data in kph. Speedometer will indicate present speed within tolerances. Display will show 0 if input in not received. If input is invalid for one second or more, or if speed is 0.

tAc
Displays the tachometer data received from the PCM via the SCP network within tolerances. Tachometer will indicate present RPM. Display will show 0 if input is no received, if input received is invalid for one second or more, or if engine RPM is 0.

FUEL
Displays the code (0-255) for the fuel sender input to the HEC. The fuel gauge will display a filtered fuel level value. This filter will keep the pointer from moving suddenly or erratically.
255 open send +/- 0
232 full stop +/- 0
215 Full mark +/- 10
178 3/4 mark +/- 8
138 1/2 mark +/- 7
93 1/4 mark +/- 5
41 E mark +/- 4
54 Low Fuel (0-59)
0-18 short (0-20 max)

OIL
Displays the code (0-250) for the oil pressure switch input to the HEC. Oil pressure gauge will indicate present oil pressure. Normal oil pressure (greater than 6psi) will display a value between 000 and 176. A low oil pressure or an inoperative engine oil pressure switch (less than 6 psi) will display a value greater than 176.

dEGC
Display of engine temperature in Degrees C input from cylinder head temperature sensor.
49 C "C" mark
60 C Normal band start
120 C Normal band end
-40 C No SCP message for 5 seconds

bAtt
Displays the code (0-255) for the battery voltage input to the HEC. Battery voltage gauge will indicate present battery voltage.
93-102 6.2-9.1 volts, low voltage
115-124 8.5-10.7 volts, Normal band start
215-225 15.8-18 volts, Norm band end
230-241 16.9-19.1 volts, high voltage

rhEo
Displays the present decimal rheostat dimming input, 0-255 (used when requesting assistance from the hotline)

rhi
not used

rhS
not used

rho
not used

Cr
Displays the current RUN/START sense input. Display will show -h for high input with the ignition switch in the START position and -L for low input with the ignition switch in the RUN position.

PA-PE7
not used

GAGE
Repeats the display cycle

Source: Helms 99 manual.

 

Also, just thought of this, did you check Battery Junction Box ( aka BJB / engine compartment fuse panel ) fuse #11.
This is the fuse for the regulator field.

 

Wow I'm an idiot for not checking test mode... Anyway, I disconnected the battery, let it sit, reconnected the battery, let the truck re-learn its idle, and then tested it. Here are the results...

- In Park, at idle, with no accessories on: 184
- In Park, at idle, with A/C on: 184
- Driving at 35mph with no accessories on: 184
- Driving at 35 with A/C on: 183
- Driving at 35 with ALL accessories on: 182
a. Radio, subs, head/fog lights, and A/C
- Driving, engine floored to 50 mph from stop w/ everything on: 182+/-

I checked all interior and exterior fuses related to the ABS. I then checked fuse #11 (engine box - regulator). All fuses were in perfect condition.

During my tests, I was NOT able to replicate the problem. Everything ran fine and the truck ran great. I find this odd because when this was first happening earlier today, I was able to turn the truck off and on several times and was able to replicate the problem. Don't get me wrong, I'm thrilled my little test drive went well... I just see the problem coming back in the future.

SSCULLY, thank you for your help and quick responses. Also, am I correct in assuming that since the truck is now off, any ABS codes that were thrown are now erased and cannot be read (assuming there were codes thrown)? Since I apparently cannot replicate the problem, I'm guessing it will be hard to have codes read and/or to have an expert diagnose the problem at a shop?

If anyone else has any advice, please chime in!

 

The relearn is a bit more than just the idle. You should have taken it for 2 drive cycles.

If the ABS light is off, the problem is not being seen. The ABS is a bit different than the DTC codes. It does not take 2 driver cycles to clear those. Could have been an over voltage problem with the ABS pump ?? That is a complete SWAG.

Next few times you start it, start it in DTM, and watch it. Might be helpful if the problem comes back.

 

Good to know! I just followed the relearn process in the manual. I'll take it for another drive in a little while.

I read some other places about the ABS pump. I'll do a little more research on that. Don't worry, your wild guesses are better than anything I can come up with!

I'll just run it in test mode for a while and see what happens. I'll bump the post if anything changes. Thanks again for your help!

 

If nothing else status the thread by End Of Week.

Nothing personal, hope I don't hear from you until Friday

 

your ABS is related to your charging symptoms. The ABS light will come on if:

 

SSCULLY: Will do... I appreciate your sense of humor!

Patman: Excellent post. I read that somewhere else but I couldn't figure out exactly why they are so closely related. I guess it doesn't matter why, only that it's just the way it is haha. But, with that said, your post is extremely beneficial because now if it acts up again, I can at least rule out the ABS system with a decent amount of certainty. So, with that said, I'm thinking the alternator was pumping out too much power or the battery was being allowed to overcharge. My question now is, are either of those problems possible? Would a cheap battery be more prone to overcharging or is it the truck which is more responsible for the charging? Can an alternator crank out too many volts? It would seem to me that that if watts and amps stay constant on the alternator, so should the volts. I guess this leads me to conclude that the battery may be defective. Ugh... I'm thinking way too hard about this. I'm going to try to relax and just see what happens and I'll update y'all by the weekend! Since there are no posts about the actual fixing this specific issue, maybe it was just a fluke (but I really don't writing it off to a fluke).

Thanks again for all the great info!

 

Hmm... Nevermind my volts-amps-watts rant. I don't think that really make sense here. I guess I was just wondering if it's possible for the alternator to vary its output to the battery in a manner that could overcharge it.

 

yes the alternator varies output, and could overcharge if the voltage regulator is bad

I dont think the battery is the problem at this point

 

I see... I think you're right. It's probably not the battery. Especially since the truck was running at the time this happened. Would the CEL come on if the voltage regulator was bad? I'm guessing not since the battery light would be more indicative of a problem (either too high or too low). The observation continues!

 

The "Check Engine" for the charging system is the charge gauge in the cluster, and being able to read it on the odometer display in DTM.

Just like the ABS has it's own indicator.

This is how the 97-03 ( and your '04 model and the '04 L ) reported errors.

 

Hey TxTechF150,
Just wondering if you found the cause of the problem or if it just went away on it's own?
Got the same problem on my 2004, both Battery and ABS lights are on.
I'm going to get the battery and Alternator tested tonight.
The guy I bought the truck from said that he just replaced the alternator so I wonder if it's defective.
I took out all the ABS sensors and they all looked fine. I am also going to ohm test them tonight as well.

Anyone know a cheap ABS code reader? Cheapest one I can seem to find is $100+ and I hate to spend that kind of money for probably a one time use device just so it can tell me I have a bad $100+ part that needs replacing.

EDIT: Well my battery tested fine but the alternator showed low Stator volts so I'm getting a replacement to see if that takes care of my issues.