ABS Light

[DavidS827]

My ABS light recently started to come on. It doesnt come on every time I drive and although im not sure of this, it seems to come on after driving down gravel (bumpy) roads. I have an 02 f150 5.4L with about 168k miles. Where would you start looking? I hear the rear abs sensor goes out first on these. Also…the hubs on this arent even a year old….not sure that helps either, but figured I would throw it out there because i think new sensors come with them.

Topic

[jcc007]

I have a 2003 Saturn vue, and I replaced the rotors and the Brake pads..

[jcc007]

Quoted From Beefy:

Probably a dumb question, but do you feel the grinding noise through the pedal or through the steering wheel/chassis?

The brake pedal, and only happens once in a while, but the abs light stays on the whole time.

[johnzcarz]

What you may be feeling is the abs activating. Even though you should use a scope to see the waveform from the abs sensors, you might want to just try and measure the resistance of each one and see if you find 1 that’s different than the others. All you have to do is follow the wire back from the sensor to the connector and measure it there. Check resistance between the 2 conductors as well as between each conductor and a good ground.

[jcc007]

Quoted From johnzcarz:

What you may be feeling is the abs activating. Even though you should use a scope to see the waveform from the abs sensors, you might want to just try and measure the resistance of each one and see if you find 1 that’s different than the others. All you have to do is follow the wire back from the sensor to the connector and measure it there. Check resistance between the 2 conductors as well as between each conductor and a good ground.

That’s true, Im going to call autozone and see if they do abs scans. If not ill have to take it in at a garage and have them scan it. Then get the codes.

[EricTheCarGuy]

+1 on it being the ABS activating so I wouldn’t worry about the ‘grinding noise’ and I’m also for pulling the code(s) to see what you have that’s the way the system was designed to help aid in diagnostics therefore it sets a code for a particular part of

[jcc007]

Thanks, dreamer 2355, what you just said is kinda greek to me, But Ill have to do my homework. I wonder what codes I should tackle first? I changed the transmission fluid in the vue, about 2 weeks ago and weird how I just got this code now, the P0700..

p0431 and p0421 has to explain why me exhaust smells so bad, Do you think it could be an 02sensor? or possible a mass air flow sensor failure? Also if there is a vacuum leak, Im thinking of hooking up a hose near the throttle and blow smoke into that area and see where the smoke comes out of.

Man! 7 codes is NOT good, Im out of cash due to the holiday last month, so Im going to have to tackle what code is the most important and go down the list.

Im kinda shocked about P0700 code, could it be the valvoline max transmission fluid I changed with or have enough? I checked the fluid and its not low or not high it has the right fluid level.

[dreamer2355]

Some of the codes could be the result of other codes if that makes sense?

But without having the right equipment these days, its a guessing game.

I would not assume anything without testing and gathering evidence.

If you search online, maybe Google, you might be able to find testing methods for your fault area by using a DVOM and wiring diagrams.

But if your ‘in over your head’, it might be a bad idea to take it to a facility with fully trained technicians.

[EricTheCarGuy]

Yea first I would check for vacuum leaks to satisfy that ‘lean’ code which could be the result of the IAC malfunctioning (famous on that V6 engine) but first check for vacuum leaks just to be sure. As for the the transmission code I wouldn’t worry about that as of yet especially if you have had a ‘low voltage’ situation like a dead or low battery, this can also cause multiple codes to set like that, think about it the computer speaks in the language of voltage values, if the voltage is low or irratic it doesn’t know what anyone is saying and can ‘freak out’ and set a bunch of codes. In summery check for vacuum leaks and clear all the codes, if you don’t find any vacuum leaks and the codes don’t come back right away I wouldn’t worry about those for now. As for the ‘U’ code I would clear that out and then recheck to see if it comes back, if it does the first thing I would do is check all the fuses, if the ABS fuse or one of them is blown it can cause that code to set and the ABS light would remain on.

[jcc007]

Hey guys, Thanks for all your help with this!! Thanks Eric, I will do a Vacuum leak test this week with smoke but wonder what area I should blow it into. Also, you guys are absoulty right, With the Leak it is setting off other codes. I checked the ABS fuses and non are blown, Im thinking that one of the sensors could be off.

Thanks, everyone!! James

[jcc007]

Hi Guys, well here is the codes that I have when I hooked up my OBDII scanner, first time I had 5 now I have 7.. Thankfully the ABS one is on here. Check it out.
P0171Fuel Trim System Lean (Bank 1P0174Fuel Trim System Lean (Bank 2)P0421Warmup Catalyst Low Efficiency (Bank 1)P0431Warmup Catalyst Low Efficiency (Bank 2)P0507Idle Air Control System RPM Higher Than ExpectedP0700Transmission Control System PerformanceU2108Lost Communication With The ABS/TCS Module So its code U2108.. Now does anyone think that is a sensor that malfunctioned? Thanks everyone for your help! 🙂

[dreamer2355]

Any type of ‘U’ codes are CAN Bus network errors. You will need some serviced information and flow testing charts to diagnose those codes.

I would not assume the ABS module is bad. It code be a wiring issue depending on how the system is wired and the type of network used.

If both banks are running lean, i would take a look at fuel pressure first and compare against factory specifications.

I would also be checking for vacuum leaks around the lower intake manifold and after the MAF sensor.

Having access to a scan tool that shows PID data particularly for fuel trims, o2 readings and MAF readings would be very helpful.

Also with a bi-direction scan tool you could activate the IACV and see what response you receive.

[dreamer2355]

When i use a smoke machine, i usually find a hose that routes directly to the intake manifold.

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