Disconnecting Battery

O

olhass

Member
Joined
Jul 15, 2010
Location
Virginia
TDI
2004 Jetta GLS
This is probably a very simple/silly question but, since I don't know the answer:

My dad recently gifted me the title to the 2004 Jetta TDI Wagon I've been driving since high school, and now I'm responsible for all maintenance. I had my first Check Engine Light come on the other week. The dealer told me it was the result of a bad glow plug relay, and wanted $550 to fix it.

I thought that was preposterous, and looked around a bit and discovered that it looks not too tough to do on my own. My one question is though, since I'll have to disconnect the battery to replace the relay, will this erase valuable data in the ECM? My Haynes manual seems to think that this will cause important data to be erased? Will I be ok just disconnecting? Should I get a memory saver device?

Any advice would be great,

Thanks
 
Lex4TDI4Life

Lex4TDI4Life

Top Post Dawg
Joined
Jun 22, 2006
Location
NorCal
TDI
2001 Golf-Ute TDI GLS 5spd Manual
I am guessing the Haynes manual assumes you will never need a new battery:rolleyes:

No, disconnecting your battery does not erase any sensitive data. Your digital clock and trip odometer will reset. Your radio might go into safe mode, which will necessitate the entry of your radio unlock code, which should be in your owners manual.

olhass said:
This is probably a very simple/silly question but, since I don't know the answer:

My dad recently gifted me the title to the 2004 Jetta TDI Wagon I've been driving since high school, and now I'm responsible for all maintenance. I had my first Check Engine Light come on the other week. The dealer told me it was the result of a bad glow plug relay, and wanted $550 to fix it.

I thought that was preposterous, and looked around a bit and discovered that it looks not too tough to do on my own. My one question is though, since I'll have to disconnect the battery to replace the relay, will this erase valuable data in the ECM? My Haynes manual seems to think that this will cause important data to be erased? Will I be ok just disconnecting? Should I get a memory saver device?

Any advice would be great,

Thanks
Click to expand...
 
D

d2305

Veteran Member
Joined
Jun 26, 2004
Location
Pensacola FL
TDI
14 Ram EcoDiesel
On an 04 you don't need the code. There is a recall on the glow plugs, but the dealers screw it up.
 
J

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Can you tell us what the DTC is? I've read that the GP relays rarely go bad, and I just want to be sure that the dealer is not throwing parts at the car.
 
oilhammer

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
I too would want to know what the actual DTC is.

Also, that car was (is?) under recall for glow plugs and a reflash to control them.
 
S

Sc0

Veteran Member
Joined
May 21, 2000
Location
Houston, TX USA
TDI
'02 Golf GL 5sp Candy White Tan cloth interior
Need more info...

I have had a glowplug light on since around 30k miles, some 225k miles on it now... Sometimes it appears and sometimes it doesn't. Had intermittent glowplug codes due to VW crap design of the glowplug connectors. Cleaned the terminals and squeezed the connectors and off the light went for about a month and same errors again, I just clear the light when it pops up. (In Texas you can have CEL while getting an inspection unlike a gasser due to it just being a safety inspection.)
 
O

olhass

Member
Joined
Jul 15, 2010
Location
Virginia
TDI
2004 Jetta GLS
Sorry, busy day. Well, the other week the CEL came on. At the same time, the turbo ceased working, and its been a bit slow to start.

The dealership came up with the following dtcs

Turbo/Super Charge Wastegate Solenoid
Low Input/SHort to ground


Radiator Exhaust Gas Recirc switch over Valve
Open Circuit/short to ground

Camshaft Position Sensor -G40-
No Signal
Sporadic

Intake Flap Motor
Open Circuit/short to ground

Motor for Intake Flap
Falty

Activation Glow Plug Control Module
Electrical malfunction

The dealer said all of these things were symptoms of a bad glow plug relay. However the part that showed up at Advance is not the same as under the cowl. Nothing that looks like it on the relay panel either. I think the dealer meant to say GP Control Module.

Any input would be great!
 
jcrews

jcrews

Top Post Dawg
Joined
Jul 28, 2007
Location
Round Rock, TX - VCDS
TDI
All gone
There could be a problem in the EGR assembly or the wires that attach to the intake manifold. You can use an ohm meter attached to ground and terminal 34A in the fuse block to check the circuit resistance. If unplugging a single component causes the resistance to approach an open circuit (and it should have very high resistance with the power off), that component is probably at fault and should be examined.
 
P

procupine14

Veteran Member
Joined
May 20, 2010
Location
Kansas City, MO
TDI
2003 Beetle 5sp
I agree that you should probably get the car to an expert if for nothing else to give you a proper diagnosis and peace of mind. After that you can fix whatever needs fixing for a reasonable price instead of the dealer throwing parts at the problem.
 
O

olhass

Member
Joined
Jul 15, 2010
Location
Virginia
TDI
2004 Jetta GLS
From what I'm reading, and seeing in the wiring diagram though, the GP relay doesn't just deal with the glow plugs. The glow plug has one output that goes directly to fuse 34, which also feeds to the air mass meter, the commence injection valve, the exhaust gas recirc valve, and the charge pressure control solenoid (which should open the wastegate for the turbo at the proper pressure, if I understand correctly). So if the GP relay is shorting and blowing that fuse, couldn't that explain the problem?

Not trying to be contentious, but it seems plausible to my limited knowledge.
 
jcrews

jcrews

Top Post Dawg
Joined
Jul 28, 2007
Location
Round Rock, TX - VCDS
TDI
All gone
What you're seeing is a representation of internal splices that connect fuse 34 (the power supply) to all the protected devices. The GP controller doesn't go bad often. Check the wiring to all the other items, especially on the motor, where they can get chafed by vibration.

In communications, cabling faults account for 70% of failures.
 
O

olhass

Member
Joined
Jul 15, 2010
Location
Virginia
TDI
2004 Jetta GLS
You were right! The wire to the wastegate solenoid rubbed through the insulation on the firewall. All the car wound up needing was a $5 connector!
 
0

04SlvrJetta

Veteran Member
Joined
Aug 1, 2007
Location
Wheeling, WV
TDI
15 Passat SE DSG
Nice job! I'm glad I took the time to read your thread. One thing you might care to know...our cars don't have wastegates. They have variable geometry (i.e. adjustable vane) turbos.
 
You must log in or register to reply here.
Top