View Full Version : Please Help 2002 Passat TDI 130 - N75 Valve / ECU Problem - AVF Engine code
mickeybo
06-09-2011, 10:01 PM
Hi,
I have a problem with my passat with the N75 not operating. Checks done so far:
1. Checked for vaccum at the N75 vac side - 25inhg, no vaccum on out side.
2. Replaced N75 with new valve but still not operating.
3. Checked wiring to N75 valve. Measured resistance and voltage drop from N75 valve plug to ECU plug - all fine.
4. Jumped N75 valve plug and set up to vechicle earth - N75 valve operates fine with manual earth.
The fault seems to be in the ECU. Is there any other checks I need to perform?
Any other ideas?
Thanks.
kenney
06-09-2011, 11:49 PM
Have you checked voltage to the valve?
mickeybo
07-09-2011, 12:01 AM
Yes. Getting 12v with ignition on at valve. Confirmed valve is working by jumping 12v from N75 plug to N75 terminal and temporary earth on other N75 terminal. Valve operates fine. This made me think the wiring. But wiring back to ECU from N75 checks out fine.
Peter D
07-09-2011, 06:42 AM
Do you know if your cruise control is working. Why you may ask, If the brake switch has failed or the clutch switch the Diesel direct injection system control unit J248 shuts the turbo down. The brake switch has two poles, one for the brake light and a normally closed contacts for J248 and the ABS unit. If you would like the diagrams PM me or post up your email address and I'll send them. A diagnostic code read will point to the problem. Regards Peter
mickeybo
07-09-2011, 01:29 PM
Hi Peter,
Thanks for your reply. Car does not have cruise control.
So are you saying if either of the switches you mentioned is faulty the ECU or J248 stops the operation of the N75 valve?
I will try and check the switches to see if they are ok. I think I have the wiring diagrams but if not will get back to you. I have ordered VAG-COM cable and VCDS-lite software from ebay so hopefully I can read the codes.
kenney
07-09-2011, 02:23 PM
you can check the valve with the final control diagnosis which activates the following components in the stated sequence:
1. Commencement of injection valve (N108)
2. Exhaust gas recirculation valve (N18)
3. Conditioner compressor interruption
4. Fuel shut-off valve (N109)
5. Boost pressure control solenoid valve (N75)1)
6. Glow plug relay (J52)
7. Glow period warning lamp (K29)
mickeybo
09-09-2011, 10:00 AM
Ran VCDS-Lite and the following code was displayed
1 Fault Found:
17564 - Manifold Pressure Sensor (G71): Open/Short to Ground
P1156 - 35-10 - - - Intermittent
Cleared the code a few times but it reappeared immediately. Do I need to replace this sensor or should I check the wiring also?
kenney
09-09-2011, 12:45 PM
that is probably the reason the N75 is not working,it is always a good idea to check the wiring before replacing parts
TKPeters
10-09-2011, 05:08 PM
New Map Sensor required, Darkside Developments have them for £20 + VAT + P&P
http://www.darksidedevelopments.co.uk/products/vw-3-bar-map-manifold-pressure-sensor-038-906-051-c.html
mickeybo
13-09-2011, 11:48 PM
Just to follow up - the MAP sensor seems to have solved the problem. Thanks for the help.
passat tdi130
21-09-2011, 11:37 PM
can a 3 bar map sensor be used on any avf engine..?
TKPeters
22-09-2011, 12:02 AM
Yes, they have them as standard
passat tdi130
23-09-2011, 09:18 PM
ah right cheers i thought they were 2.5bar..
passat tdi130
04-10-2011, 04:23 PM
and can this sensor just give false reading's the older it gets or is it a working or not item..!
kenney
04-10-2011, 04:49 PM
the sensor can give false readings and is one of the reasons the turbo cuts out
passat tdi130
04-10-2011, 04:53 PM
i mean the map sensor now not n75 valve..
so changing the map sensor could give better fuel economy as well..?
kenney
04-10-2011, 05:24 PM
i'am talking about the map sensor not the n75 valve
passat tdi130
04-10-2011, 07:28 PM
lol... ok well i have just changed mine for the hell of it.
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