VW Touareg multiple electrical issues
Posted to Technical Tips Forum on 7/19/2018
15 Replies
I had this Touareg in today with a complaint of transmission
won't shift. I found it unable to shift out of Park because
the interlock was inop.; after manually releasing it I went
for a drive and the trans. would not shift out of first
gear.
A code scan found lots of communication codes, and no
scanner communication with several modules including the
TCM, ABS, AWD, etc. Scope testing the data bus lines at the
DLC showed no communication signal on pins 2 and 6, and no
B+ at pin 1. After looking at a schematic I checked fuse B51
(serves DLC pin 1) and found no voltage at the fuse, also no
voltage at fuses B47, 49, 50, 52, 53 & 54. These fuses serve
the various modules that were offline, and all are powered
by the J239 Power Supply relay, located in the fuse box
under the driver's seat. Testing there, the relay had B+ on
both sides, but was not being grounded by the Access/Start
control module (under the dash, LH side). No voltage was
present at the module, so I followed the harness and found
the culprit under the driver's carpet. There are several
splices in this harness with no weather protection other
than an electrical tape wrap and all were green with
corrosion, including the J239 relay control circuit. I cut
them all out, replaced and heat shrunk them, and the issue
was solved. Two of the splices were in the middle of a
single circuit with only two wires being joined together, so
I'm not sure about the wisdom of having a splice there.
[2004 Volkswagen Touareg V6, Photo] [2004 Volkswagen
Touareg V6, Photo]
Scott Sauvola Technician Ace Auto, Inc. Winona, Minnesota, USA
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