2002 Sonata Brake and ABS Lights On
 

I have a 2002 Sonata LX with about 132k miles on it. I recently started having the Emergency Brake and ABS lights come on while driving coupled with a P1602 engine code. While the lights are on, the car drives TERRIBLY, shifting up and down randomly, erratic idling, and running higher RPMs than usual. If the lights happen to go off, the problems immediately go away. After much research, I gave in and took it to the dealership where they diagnosed everything as both front ABS wheel speed sensors being faulty. I got both the parts, and being an avid mechanic, I changed them myself. Upon starting the car I still have all the same codes and the car still drives terribly. Even after disconnecting the battery and clearing the engine code, the problems still exist. Both tone rings seem to be fine. Anyone have any better diagnosis?

Much thanks to all!

I was able to find that the connector leading to the ABS module under the hood is somewhat of the problem. Ill be taking a gander tomorrow at it again. But I still want to know why the car drives like crap while the codes are on, if anyone knows.

While the ABS light was probably from the wheels sensors, the P1602 was not.

P1602 = ECU-TCU Communication Error
A communication line exists between the Engine Control Module (ECM) and the Transaxle Control Module (TCM). The communication is through a Control Area Network (CAN). Without CAN communication, an independent pin and wiring is needed to receive a sensor information from a ECM. The more information to be communicated, the more wirings is required. In case of CAN communication type, all the information need to be communicated among control modules such as ECM and TCM use CAN lines.

You probably need a new TCM. At this point, it probably costs more than the car is worth.

Check the sensor wires / under hood connector for exposed copper. Also check fuses for ABS and Engine / ECU. ABS and engine control fuses should all be located in under hood junction box on driver's side. (If not mistaken, there will be three ABS fuses, ABS2 - 30A, ABS1 - 30A & ABS - 10A.).
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Thanks for the responses guys. The odd thing is, if wiggle the connector going to the ABS module, I can get the codes to turn off, including the engine code. The engine code only occurs when ABS and Brake lights come on, and the terrible drivability only occurs when the ABS and Brake lights are on. The fuses and all that seem to be in working order.

None of these symptoms occurred until I hit a small pothole in my yard, then it all when to crap.

Perhaps the connector itself is defective. May have to open and reset the terminals inside.
Just to understand, you changed the front speed sensors which wire harness is connected to the sensor, so the wiring is new, correct?
You stated that after hitting a pothole, is what caused problem to begin. I'm not that familiar with 02 Hyundai however, is there something other than the speed sensors that may have been damaged underneath chassis after hitting pothole (ABS Hydraulic module / pump etc.)?
Would you have any photos of the suspected connector and what connector is attached to?
I believe many owners of different make vehicles also experience the same thing after hitting a pothole. After vehicle was serviced, vehicle would run rough until computer relearned idle setting etc. Others had computer reset after repairs which fixed the problem.

The intermittent nature of the problems makes me think that either the connector is faulty or the ABS Module is faulty. Yes, I changed both front ABS Speed Sensors, and checked all the other parts withing the system. I opened up the connector and cleaned it as best I could, as well as the pins going to the module. The problem still persisted, although much less often. After work today, I simply pulled the main ABS fuse, (fuse 3) and although the ABS and Brake lights are still on, the drivability is just fine. No engine codes, no weird idle or shifting. Yeah, I don't have ABS or TSC, but until I can fully diagnose and find parts needed, this will treat me well.

I've never had to use the ABS or TSC since I've had the car, and my previous car didn't have ABS stock, so I'm use to it.

Anyway, I really appreciate all the help! If i find the problem, I'll let you all know.

2 things:
1 - P1602 has nothing to do with the ABS/TCS. If that code came up there is a problem with the transmission control module. Go back and scan for codes again. Make sure that is the correct code.

2 - A problem with the ABS system would not create drivability problems.

Something else is wrong to be causing drivability issues.

My apologies, became focused on the ABS/TCL light that I completely forgot about the P1602 error that NovaResource went into detail about.
I believe the ECM control module and relay are located in dash behind radio. Maybe check the following fuses: fuse #6(20A) is ATM RLY and fuse#7(30A) is ECU RLY.

You stated your no longer experiencing drivability issues since removing ABS fuse or issue stopped before removing fuse?
Problem may be with one of the two wires between the ECM and the TCM being frayed through the insulation on a metal component, which may be causing the driving issues. Other potential issue could be with the ECM however, problem that is intermittent most likely indicates issue is with the wiring and not the module. Harness may be frayed in the transmission valve body. Perhaps dealer could refresh / flash the ECU?
There are a couple TSB (Technical Service Bulletins) regarding ECM but with error code P0139;

TSB Reference #0236037
NHTSA Reference#10002220
Date Reported: DECEMBER 01 2002

TSB Reference #0336019
NHTSA Reference#10004433
Date Reported: AUGUST 01 2003

The drivablilty problem seems to have completely gone away when I pulled the fuse. I decided to do some testing this morning. I started the car, no ABS fuse (the lights on because of it), and with no engine codes. Drove around for about 10 minutes with a full range of speeds and turns; no problems whatsoever. I got home, put the fuse back in, started the car to no lights. Shortly after starting, ABS/Brake lights came on, followed by engine code P1602, and crappy drivability. Came home, cleared the codes, started the car to the ABS/Brake lights already on, and after 10 seconds or so, same engine code. Still crappy performance. About 5 minutes into the drive, the ABS/Brake lights turned off for about two minutes, and during that time, I had no problems with the driving. Lights came back on and problems came back. Got home cleared everything, and pulled the fuse. Started to the ABS/Brake lights(because of the fuse), no engine code, and drove around for 10 minutes with no problems, and it even feels a bit better than the car did before the problems started. Did the no fuse test one more time with the same results.

Even as someone who has years of electronics experience, and years of working on cars, I can't make any sort of sense to why this is happening in this way. I can't see the ABS system causing the drivability problems, but the engine code only come up during that time.

I'm at a loss. All I know is that undoing the fuse seems to be working fine for me.

I only have 3 conclusions:

1) My car has serious gremlins.
2) Black magic.
3) A fourth dimensional wormhole continually opens up within my engine electronics causing a massive flux in the space time continuum, causing the car to run like crap.