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Codes u0121 the speedometer does not work AT BRAKE ligth ABS are on

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My 07 mazda6 as four codes u0101,u0155 u0121,u0073,u0100 and stuck in 3rd gear please help

You'll need to get a good auto electrician to look at this. The codes suggest a failed ECU, the brain reading all the engine sensors. If this fails, the car is unusable as the ECU won't let the vehicle work.
Codes read as:
U0073 - Control Module Communication Bus "A" Off
U0100 - Lost Communication With ECM/PCM "A"
U0101 - Lost Communication with TCM
U0121 - Lost Communication With Anti-Lock Brake System
(ABS) Control Module
U0155 - Lost Communication With Instrument Panel
Cluster (IPC) Control Module
I have very little experience with gearboxes so I can't really help with the 3rd gear problem.

May 27, 2018 | Cars & Trucks

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I got the cables switched when I jumped my 2006 chrysler 300 touring. The transmission is stuck in a low gear, the speedometer doesn't work, the power windows don't work, the abs light is on, the brak

Google the codes for your vehicle

Lost communication with the pcm,buss & other modules

Check all your fuses,fusible links & any ties bars in or under
the fuse & distribution boxes

Would help to have a factory wiring diagram for your testing

Sep 30, 2014 | 2006 Chrysler 300 Touring

1 Answer

Codes u0121

The brake controller wont talk to the ECM, it could be the cable or the brake controller.

May 07, 2014 | 2005 Mazda 6 2.0

1 Answer

ABS indicator lamp lights up and indicator km(in speedometre) is not lit

try pulling battery for ten minutes or so and see if that clears any of the codes if not use a obd11 code reader and that should give you a correct answer

Apr 22, 2014 | 2011 Ford Ranger

1 Answer

DTC U0121 - Lost Communication With Anti-Lock Brake System (ABS) Control Module

If you clear the code does it come right back AND is the ABS light illuminated on dash?

Apr 17, 2014 | 2011 Ford Ranger

1 Answer

Hello, I have a problem with my Saturn Astra 2008,

U0121 Lost Communication With Electronic Brake Control Module

As with most trouble codes, the U0121 code gives a general diagnosis. Review the info on this link. Look through the service bulletins. The problem could be a loose plug or faulty wiring to one of the modules or between modules that are listed in the article. I hope this helps somewhat. Good Luck......

Apr 03, 2014 | Saturn Astra Cars & Trucks

1 Answer

Same problem. ABS light, Brake ligth. Speedometer not working. I un hooked the nbattery for a while and all seem to be woring for now? Any ideas

Hi these trucks are know for the front hub bearings to fail., the wheel speed sensor is located in side of them and serviced as a unit. Mostly the set the abs light while doing slow turns your will hear the abs motor and feel the break pedal pulsate.

Aug 30, 2010 | 2000 Chevrolet S-10

1 Answer

Abs light, brake light, engine light stay on but do not flash

Well, that sucks, for sure. The only commonality I can see between the engine, abs, brake light and speedometer is possibly a bad vehicle speed sensor. But when you throw in the codes for lost comm and cluster error, that muddied the water a bit. I am sure that there are separate fuses for the trailer wiring harness (my 04 chevy has separate fuses, surely an 09 dodge does) so I doubt trailer wiring could have done all this. A lost comm could be caused by a blown fuse. I would inspect every single fuse I could find in the entire vehicle, also, I have researched your problem a bit and have found a couple possible fixes. One is that the abs sensor on the rear differential is known to be sketchy and needs to be changed. The other is cleaning any ground cables that are connected to the fuse box on the front left fender. I hope this helps!

Mar 02, 2017 | 2007 Dodge Ram 2500 Mega Cab Laramie

2 Answers

Speedometer stoped working ,at first sometimes it worked sometimes did not now wont work at all,allso abs and brake and motor light on when speedo wont work,2001 dodge ram 4x4 with 360 engine

Probably either your PCM or Vechile Speed Sensor. The VSS sends an AC (alternating current or sine) wave to the PCM and according to the frequency of the wave, tells the PCM the speed with which the vehicle is moving. It will be mounted to your transaxle, and I would look into this before the PCM.

Jul 22, 2009 | 2001 Dodge Ram 1500 Truck 2WD

1 Answer

Emission test found some trouble codes

U0121 Communication error to ABS HU/CM

Apr 06, 2009 | 2005 Mazda 6

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