'03 Elantra OBD II code & M/I monitors

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#1
Please fill out the following to ask a question.

MAKE: Hyundai
MODEL: Elantra
YEAR: 2003
MILES: 120,000
ENGINE
: 2.0L
DESCRIBE ISSUE....
The check engine light has been randomly coming on and going off for about three years on my 2003 Hyundai Elantra. This car is only driven an average of twice a week for 4,000 miles per year.

Up to now I have managed to time getting an inspection sticker which is now due in one month.

A scanner gives codes P0600 [ serial communication link ] & P1602 [ transmission control module ]. The I/M oxygen sensor and EVAP system both show as not ready. I don't understand the relationship between these and am at loss as to what needs done to correct. Changing the oxygen sensor seems like the logical thing but don't want to just start changing parts. Also, the fuel mileage has recently decreased over 3 mpg.
 
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#2
There is a lot of info online. Here is a synopsis of some of that info:

  • OBD II P0600 Generic Code
PCM Serial Communication Link Malfunction
What does this mean?
The PCM or Power Train Control Module performs many vital functions in a modern vehicle, such as management of the Fuel System, Ignition System, Transmission, Anti-Lock Brake and Traction Control systems. The Serial Communication Link enables the control modules to 'talk ' to each other.
When the code P0600 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM has lost communication with 1 or more other control modules.
Symptoms

  • Check Engine Light will illuminate
  • ABS/Traction Control Light may illuminate
  • Transmission Light May Illuminate
  • Vehicle may not perform and/or shift properly
  • Decrease in fuel economy
  • In some cases, there may be performance problems, such as dying when coming to a stop and/or misfire-like symptoms
  • In unusual cases, there are no adverse conditions noticed by the driver
Common Problems That Trigger the P0600 Code

  • Defective PCM (Power Train Control Module )
  • Defective PCM data bus wiring/connections
  • Defective PCM data bus ground circuit(s)
  • Defective PCM or other control module controlled output devices
  • Defective CAN bus communication
Common Misdiagnoses

  • Ignition problems whose root cause is a defective PCM
  • Fuel Injection problems whose root cause is a defective PCM
Polluting Gases Expelled

  • HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
  • CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
  • NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog
P0600 Diagnostic Theory for Shops and Technicians

The PCM shares data input with several different systems and if the communication link between them fails, then 1 or more systems will shut down. The cause of the P0600 code may be a defective data bus, a defective data bus connection, or a defective control module. If you have to replace a module, make sure that you inspect all of the module's output devices and wiring for shorted circuits or else the new module will fail in short order. When diagnosing a P0600 code, it is important to record any other codes and the P0600 freeze frame data.
________________________________________________________________________________________________________
OBD II P1602 Hyundia specific Code

Possible causes
- Faulty Transaxle Control Module(TCM) or Engine Control Module(ECM)
- Transaxle Control Module(TCM) to Engine Control Module(ECM) harness is open or shorted
- Transaxle Control Module(TCM) to Engine Control Module(ECM) circuit poor electrical connection

Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)

P1602 Hyundai Description
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.
 

billr

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#3
The PCM may not be able to conduct the O2 or evap tests because of the com/TCM issues, those should be addressed first. Unfortunately, I don't know if this can be DIY job; maybe dealer only.
 
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#4
Thank you for the detailed response Jack. I have suspected a wiring connection problem due to the come and go nature of this issue and a shifting problem that I did not mention. There is also more involved in this story but I did not want to post too much info in my post and cause confusion. At this point I am going to try and track down the wiring between the ecm and the tcm. I'll search the web for layout and wiring diagrams and re-post the results.
 
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#8
As a follow up to '03 Elantra OBDII code & M/I monitors;
What I think I know so far and resulting additional questions ......
I enlisted the help of a local shop owner for diagnostics help and he discovered a voltage problem
with the TCM. Looking at a replacement a new one is $800. which is out of the question.
Found a used one for less than $50. that says compatible with 2003 thru 2006 though with a broken bracket.
Existing is a # 95440-39231
The found item is a # 95440-39232

1) Is it simply a matter of swapping around interiors and cases?
2) Also, in looking at a schematic drawing there is also shown a separate control relay [ location unknown ].
Does this relay need to be changed along with the TCM?
3) Lastly, does the TCM need to be programmed after changing it out and if so what is the
procedure for doing this?

Any additional insight on this would be much appreciated.
Regards,
Richard Simpson