Difficulty in Connecting Code Reader

  • 4 CYL
  • FWD
97 Jetta GL 2.0 –connected a Code Reader (OBDII compatible) but unable to establish any communication-everything else works as normal-
Is there a main fuse which protects the diagnostic link
Do you
have the same problem?
Sunday, November 28th, 2010 AT 7:23 PM

1 Reply

Yes there's a fuse, and this is a common problem, so check this first. Also, here's a technical service bulletin for your vehicle:

Diagnostic Testers, No Communication, Possible Damage Due to Improper Installation of Aftermarket Accessories

As per TSB Group 01; Number 02-03; Dated June 10, 2002

A condition may exist, on all models equipped with OBD II, where there is no communication with diagnostic testers or scan tools. This may be caused by improper installation of aftermarket accessories (including radios).

Improper installation of aftermarket accessories (not factory approved) in m.Y. 1996 and newer vehicles may:
- Affect various vehicle systems connected to the OBD system!
- Cause severe damage to V.A.G. 1551/1552 and other scan tools without over-current protection!

DO NOT attempt to connect any scan tool which is not equipped with over-current protection to any vehicle in which an aftermarket accessory has been installed before checking communications through the Data Link Connector (DLC) by using the VAS 5051 or VAS 5052 Diagnostic Tools (which are protected against excessive current).

Prior to connecting any scan tool (not equipped with over-current protection):

* Check for installation of any aftermarket accessory (which may be improperly connected to vehicle OBD wiring).

If aftermarket accessory is installed:

* Attempt OBD communication using a VAS 5051 or VAS 5052 Diagnostic Tester.

If OBD communication is possible:

* The installation of the aftermarket accessory will not interfere with OBD communication through the DLC.

If OBD communication is NOT possible:

* Scan tools without over-current protection, (except the VAS 5051 or VAS 5052 Diagnostic Testers) cannot safely be connected to the vehicle DLC until the cause for problem is determined and eliminated:
* Remove (disconnect) the aftermarket accessory and attempt communication again.

If OBD communication is possible:

* Continue diagnosis (using preferred diagnostic tester) with accessory disconnected.
* Accessory installation should be corrected to ensure no future communication problems will occur.

If OBD communication is NOT possible:

* Additional diagnosis is required to determine the cause of the communication failure.
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Sunday, November 28th, 2010 AT 7:39 PM

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