2000 Volkswagen Jetta Blown fuse

Tiny
MAXWELL0925
  • MEMBER
  • 2000 VOLKSWAGEN JETTA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 149,414 MILES
My car wouldn't start. After inspection, I noticed no fire was coming from the coil. I checked and had to replace the engine management fuse that went to the coil. When I turn the switch on the fuse immediately blows. I removed the fusebox and checked the wire, traced the wire from the coil back to the firewall, and made sure the grounds under the hood were tight. I put a bigger fuse in(25amp) just to see if car would start and it did. I shut it off and removed the bigger fuse because I know the 15 amp fuse is there to protect the car. Do you have any suggestions? Thanks!
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Wednesday, September 29th, 2010 AT 5:38 AM

3 Replies

Tiny
KHLOW2008
  • EXPERT
Hi maxwell0925,

Thank you for the donation.

Is it Fuse # 29 that is shorting out?


http://www.2carpros.com/forum/automotive_pictures/192750_Fuse00JettaFig06_1.jpg



Designated fuse should not be changed with a higher rating to protect the components in the circuit and you are correct to avoid doing that.

The fuse is used for the PCM and ignition coils and PCM would seldom short out and still run so the most likely cause would be from the ignition coils.

Check the wireharness for exposed wires that might be shorting to ground intermittently.

Have you tried to retrieve for trouble codes?
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Thursday, September 30th, 2010 AT 2:01 PM
Tiny
MAXWELL0925
  • MEMBER
This is a great site! I replaced the 15 amp fuse and now it's not blowing. The car starts, runs bad, and cuts off. I towed it on a dolly to Autozone and the code was P0725. I checked the wires from the coil to the firewall visually, cleaned the grounds underneath the battery, and removed the fuse box to peek at the wires in the back. I'm mechanically inclined and believe I can make this repair. What would you suggest I do? Thanks
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Thursday, September 30th, 2010 AT 3:58 PM
Tiny
KHLOW2008
  • EXPERT
Glad to know you like it here and thanks for the compliment.

Since we have a trouble code which could be related to the problem, I would advise going through the diagnostic procedures to see if we can come up with anything.

P0725 = Engine Speed Input Circuit.

Diagnostic procedures.

CAN-Bus terminal resistance, Transmission Control Module (TCM) J217 to Engine Control Module (ECM) J220 , checking.

The Motronic Engine Control Module (ECM) J220 communicates with all databus capable control modules via a CAN databus.

These databus capable control modules are connected via two data bus wires which are twisted together (CAN_High and CAN_Low), and exchange information (messages). Missing information on the databus is recognized as a malfunction and stored.

Trouble-free operation of the CAN-bus requires that it have a terminal resistance. The central terminal resistor is located in the Engine Control Module (ECM) J220.

Special tools, testers and auxiliary items required

" Multimeter.
" Wiring diagram.

Test requirement

" A CAN-Bus malfunction was recognized.
" The Engine Control Module (ECM) J220 fuses OK.
" Battery voltage at least 12.5 V.
" Ignition switched off.

Test procedure

Perform a preliminary check to verify the customers complaint. Refer to Motronic Engine Control Module (ECM) J220 , replacing

Start diagnosis

Removal

Remove the center dash panel - 1 - in the direction of the - arrow -.


http://www.2carpros.com/forum/automotive_pictures/192750_P0725Jetta00Fig132_1.jpg



Remove the right upper dashboard panel.


http://www.2carpros.com/forum/automotive_pictures/192750_P0725Jetta00Fig133_1.jpg



Remove the three center screws - 1 -


http://www.2carpros.com/forum/automotive_pictures/192750_P0725Jetta00Fig134_2.jpg



Remove the right upper dashboard panel - 1 - in the direction of - arrow A - and - arrow B -.

Pull the Transmission Control Module (TCM) J217 electrical harness electrical connector - 1 - retaining tab in the direction of the - arrow - and remove from the Transmission Control Module (TCM) J217 - 2 -.


http://www.2carpros.com/forum/automotive_pictures/192750_P0725Jetta00Fig135_1.jpg



Remove the retaining nuts - 3 - and the Transmission Control Module (TCM) J217 - 2 - in the direction of the -
arrow -.

NOTE:

" The Engine Control Module (ECM) J220 must remain connected for the following step.

Using a Multimeter , check the Transmission Control Module (TCM) J217 electrical harness connector T68 terminals 3 to 25 for resistance.

Specified value: 60 to 72 © (at approx. 20 C)
If the specified value was not obtained:

Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).
Check the wiring connection for damage, corrosion, loose or broken terminals.
If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring:
Replace the Transmission Control Module (TCM) J217. Refer to Motronic Engine Control Module (ECM) J220 , replacing .

If the specified value was obtained:
Checking wiring

If the manufacturers test box is being used. Perform the following step.

Install the Adapter F/VAG1598 (68 Pin) VAG1598/22
Install the Adapter - 68 Pin VAG1598/18. Refer to
38 AUTOMATIC TRANSMISSION - GEARS, HYDRAULIC CONTROLS for 4 SPD. AUTOMATIC TRANSMISSION 01M and 38 - AUTOMATIC TRANSMISSION - GEARS, HYDRAULIC CONTROLS for 5 SPD. AUTOMATIC TRANSMISSION 09A .

If the manufacturers test box is not being used. Perform the following step.

Remove the Engine Control Module (ECM) J220. Refer to Motronic Engine Control Module (ECM) J220 , replacing.
Using a Multimeter , check the Transmission Control Module (TCM) J217 electrical harness connector T68 to the Engine Control Module (ECM) J220 electrical harness
connector T80 for resistance.


http://www.2carpros.com/forum/automotive_pictures/192750_P0725Jetta00Fig135a_1.jpg



Specified value: 1.5 © Max.

If the specified value was not obtained:

Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).
Check the wiring connection for damage, corrosion, loose or broken terminals.
If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring:

Erase the DTC memory. Refer to Diagnostic Mode 04: Reset/delete diagnostic data
Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Refer to
Readiness Code .

End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:

Replace the Motronic Engine Control Module (ECM) J220. Refer to Motronic Engine Control Module (ECM) J220 , replacing .
Assembly is performed in the reverse of the removal.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

End of diagnosis

Additional diagnostic prodcedures wil be sent to your email as they are rather lengthy.
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Friday, October 1st, 2010 AT 7:53 AM

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