DTC 01314 ECM - No Communication error thread

[sa_seahawker]

I have been picking around in other threads to try and solve this disaster. Subsequent searches on the internets have revealed that is problem for some but I can't find a definitive answer/solution or logical troubleshooting method. In short, I'm stumped. Any help or insight is tremendously appreciated.


SYMPTOM
Aside from checking the obvious (fuses, battery, connections, etc), it would appear that my ECU isn't wanting to talk to the car the car won't start. The starter turns over but engine won't catch on. The was down for overheating/coolant issues for about two weeks (I work slow ). After reassembly, the car fired up fine and ran smooth for about ten minutes. Then I turned car off to adjust timing pulley gap with no major issues (tick marks still aligned).

ACTIONS TAKEN THUSFAR
- I've checked all fuses (all good).
- I've checked the ECU box and relays (all good).
- I've checked all wiring and ground contacts (no obvious indication of wear or shorts).
- I can hear the fuel pump hum on startup (nothing new, I've heard this all the time).
- When I go to clear DTCs, the scan always loses connection and times out and random times on every try.
- Tried logging in with Motoza tune software and it can't recognize ECU.
- Battery is fine (tested and charged at Autozone and Advanced as a redundant second opinion).
- Double checked tune.
- Coil packs are good (I wouldn't be able to even tell if they are bad until the motor actually starts).

DTCs (The Shortlist)

VIN: WAULC68EX3A107804 Mileage: 222940km/138528miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 06B-909-518-AMB.lbl
Part No SW: 8E0 909 518 AF HW: 8E0 909 018 A
Component: 1.8L R4/5VT G 0001
Coding: 0016701
Shop #: WSC 88641 551 633322
VCID: 74E9DDB314AD5ABE8FF-5120

1 Fault Found:
18010 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
Readiness: 0110 1100

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8E0-614-517.lbl
Part No: 8E0 614 517 H
Component: ABS/ESP allrad 2328
Coding: 04275
Shop #: WSC 06435
VCID: 2D5F08D7E7074B76001-5120

2 Faults Found:
01826 - Sensor for Steering Angle (G85); Supply Voltage Terminal 30
35-00 - -
18258 - Powertrain Data Bus
P1850 - 35-10 - Missing Message from ECU - Intermittent

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 8E0-820-043.lbl
Part No: 8E0 820 043 L
Component: A4 Klimaautomat 1016
Coding: 00000
Shop #: WSC 63351
VCID: 2A5503CBD6E95C4EE53-513C

1 Fault Found:
01206 - Signal for Duration of Ignition Off Time
27-00 - Implausible Signal

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8E0-920-9xx-8E2.lbl
Part No: 8E0 920 950 L
Component: KOMBI+WEGFAHRS. RB4 D35
Coding: 03200
Shop #: WSC 00999
VCID: 32651BABFE39148E5D3-513C
WAULC68EX3A107804 AUZ6Z0B0144589

2 Faults Found:
00562 - Sensor for Oil Level/Temperature (G266)
27-00 - Implausible Signal
01314 - Engine Control Module
49-10 - No Communications - Intermittent

[sa_seahawker]

Yeah. So if anyone has any tips on how to troubleshoot electronics/power supplies/ etc, I waould appreciate it.

I have close to zero knowledge or experience in dealing with electrical systems. Electrical duping rams look like spaghetti mazes to me.

I have the entire ECU box out and can see down behind the dash. But short of removing every wire in this car, I have no clue what I'm looking for.

[sa_seahawker]

Personal reference post



2003 B6 A4 1.8T harness

T10, Black, 10 pin
1. blue - generator
2. unused
3. white/grey - Oil pressure switch
4. unused
5. red/green - from pin 121 on ECU to ?
6. brown/yellow - pin 3 from engine coolant level warning light
7. blue/yellow - Engine coolant level warning switch
8. unused
9. blue/brown - Engine coolant temp sensor
10. brown/red - Speedometer vehicle speed sensor pin 2 (unused in 03)

T10a, Brown, 10 pin
1. red/blue - from injector harness to... ?
2. black/red - Oil level thermal sensor pin 1
3. unused
4. red/black - Ignition/starter switch to ground
5. black/blue - Back up light switch pin 3
6. green/red - control module with indicator unit in instrument panel insert
7. unused
8. green/yellow - connector for fuse 234, connects MAF, N112, N80, N249
9. red/grey - Oil level thermal sensor pin 3 (red/green for 03)
10. unused

T17e, White, 17 pin
1. brown/green - to pin 1 on throttle body
2. yellow/lilac - to pin 2 on throttle body
3. brown/red - to pin 3 on throttle body
4. yellow/blue - to pin 4 on throttle body
5. grey/yellow - to pin 5 on Throttle Body
6. brown - to pin 6 on throttle body
7. unused
8. unused
9. unused
10. blue/green - from pin 38 ECU to steering column electronics module
11. red/black - to pin 4 on brake light switch from ECU
12. white/red - to pin 2 on brake light switch from ECU
13. red/green - to pin 2 clutch vacuum vent valve switch
14. grey/white - from pin 1 on locking relay for starter (clutch pedal switch) to pin 2 on clutch vent vacuum valve switch
15. black/lilac - from ? to ECU
16. red/grey - from power supply relay to fuse S229 (20A)
17. unused

T17d, Red, 17 pin
1. white/yellow - pin 1 leak detection pump to ECU
2. grey/red - pin 2 leak detection pump to ECU
3. unused
4. unused
5. blue/brown - ? (03)
6. lilac/blue - to airbag control module from pin 67 ECU
7. unused
8. unused
9. unused
10. red/blue - to pin 5 on fuel pump relay
11. red/white - to ECU pin 24 to coolant fan control module
12. unused
13. orange/brown - Wire connection (low-bus)
14. orange/black - Wire connection (high-bus)
15. blue/red - reverse lamp connector
16. unused
17. unused

************************************************** ************************************************

[sa_seahawker]

more reference material for me...

[sa_seahawker]

[sa_seahawker]

[sa_seahawker]

Checked all fuses. Checked all circuits. Checked battery. Checked coils. I still have nothing but a four wheel paper weight taking up space in my garage.

Piece of shit......

I have good switched power from pin 3 and good grounds out to pis 4/5. But no start.

I can't see how the ECU would crap out spontaneously.

[customa4]

How did you test the fuses in the fuse box?

[n7plus1]

damn man....thats crazy...same year as mine...youre scaring me.

[sa_seahawker]

How did you test the fuses in the fuse box?

you pull the fuse out and see if it's blown. then you can do simple continuity checks with a voltmeter to verify juice is flowing. Did the same thing to the ECU harness.

[diagnosticator]

There is most likely a fault in the power train CAN buss from the ECU, or the ECU is defective. There is a SSP with detailed info on troubleshooting the CAN buss.

http://www.volkspage.net/technik/ssp/ssp/SSP_238.pdf

http://www.volkspage.net/technik/ssp/ssp/SSP_269_d1.pdf

http://www.volkspage.net/technik/ssp/ssp/SSP_269_d2.pdf

Right click on each URL and "Save Target as:"

You need Adobe Acrobat Reader to view the PDF files. Free download from Adobe.

Do you understand how to read the wiring diagrams, and all the info they show? Do you need help with this?

[SlickFix]

seahawker, are you using VCDS? If so, which version? There was a version recently which didn't seem to be the most stable. I would get intermittent loss of connection, too.

[sa_seahawker]

seahawker, are you using VCDS? If so, which version? There was a version recently which didn't seem to be the most stable. I would get intermittent loss of connection, too.

I'm using 12.12.2. I just emailed RossTech and explained the issue to them. Hopefully they can give me further info on the connection issue.

[onceover]

J271 relay ok?

[SlickFix]

I'm using 12.12.2. I just emailed RossTech and explained the issue to them. Hopefully they can give me further info on the connection issue.

Try this. The guy in this thread was having the same issue.

[diagnosticator]

The ECU cannot communicate with the other controllers on the CAN buss, if there is no power supply to the ECU. Since the DTCs are intermittent, and associated with an intermittent power supply to the ECU from the "30" constant battery voltage buss in the fuse panel, that is most likely the cause of the No or Missing ECU Communications DTCs. If there is no power to the ECU the car won't start, or will stop running, obviously. In addition, with no power to the ECU, the diagnostics communications between the ECU and the OBDII port on the K/L line will fail also. Can you clear all the DTCs? If not, then the faults that reoccur are hard faults.

The above circuit inside the red box outline, is the main suspect circuit for the ECU intermittent power supply fault. It connects ECU terminal pin T121/3 to the fuse panel "30" constant power supply buss, via harness connector T10m/4 in the ECU box. ( EDIT: Not applicable to the AMB B6). Look for loose terminal connections, corrosion on the terminals, bent pins or receptacle terminals, or a broken wire somewhere. A broken wire may not show on the outside, with an ohm meter test lead conneted on each end, move the wire around and see if the resistance in the wire changes from less than 1 Ohm, continuity to open circuit, or infinite high resistance, meter reading Over Limit, for the range selected, no continuity. Do not insert test lead probes into the connector terminals from the front, always back probe the terminals from the wire side of the harness connector. (You know this is a B5 AEB wiring diagram, not a B6 AMB diagram, right?)

One option to eliminate all the possible circuit defects, is to replace the wire between the fuse panel, "30", and the ECU harness connector terminal pin 3, (AMB: T121/62) running the new wire on the outside of the wire harness between the ECU and the fuse panel. (AMB: #1 threaded connection, Relay plate,) Use a new repair wire with a new terminal already crimped onto the repair wire, (from a dealership parts dept.) and insert the new terminal into the ECU harness connector at terminal location #3. (AMB: T121/62) Use a butt crimp connector to splice the repair wire to an additional length of wire to reach to the fuse panel. Use a 2" length of heat shrink tube centered over the butt crimp connector as a strain relief. Use wire ties to attach the new wire to the wiring harness to prevent movement of the new wire. I recommend using uninsulated crimp connectors with heat shrink tube for insulation. The crimp applied must be the right form and must be confirmed tight. Properly applied crimps are stronger than the wire connected. Do not use solder joints instead of crimp connections.

[sa_seahawker]

Thanks for the info.

Just I have this straight, the T121/3 pin on the ECU is pin #3 here:



But is the T10m the black connector?

Here's where I got my pin info. He listed 2003 1.8t, 2000 S4, and 2004 S4 harness pins. I saw that he listed the T10m connector was black on the 2000 S4 but didn't indicate a T10m connector for 1.8t.

http://www.audizine.com/forum/showth...ness-Explained

[diagnosticator]

Yeah, I don't know if the T10m (black) connector is used on the B6 AMB, I will have to look on my wiring diagrams and post back here. The T121/3 terminal is the #3 terminal shown on the ECU pin out diagram. All of the ME 7.5.x ECUs have the same pin out arrangement. Note that T121 is actually two connectors on the ECU. EDIT: The AEB ECU is not a ME 7.5.n version. It is a earlier ME 7.1.n, IIRC. All ME 7.n.x ECUs have the same pin out layout, but pin functional assignment can vary between versions.

[diagnosticator]

OK, on the B6 1.8T AMB ECU wiring diagram, the "30" +BATT power supply connection at the ECU is at pin #62, (T121/62,) NOT pin 3! Pin 3 is a "15a" key switched +12 volts power supply to the ECU. Pin terminal #62, connects to the "30" always energized +BATT buss at the #1 threaded connection on the relay plate under the dash. There is no 10 pin harness connector in the "30" power supply circuit to the ECU. T10 (Black) in the ECU box, is not associated with the "30" circuit connection to the ECU for the AMB. The references to this circuit shown in the wiring diagram and as discussed above do not apply to the AMB. Circuit diagnostics and circuit wire replacement procedures are the same regardless.

[sa_seahawker]

Okay. I just opened up T121 connector. I have solid good power to pin 62. If not power or ground, then bad ECU?

[diagnosticator]

Okay. I just opened up T121 connector. I have solid good power to pin 62. If not power or ground, then bad ECU?

That is the only possible cause for the DTC remaining, provided the power supply on pin terminal #62 is not intermittent. Is it true that the Intermittent "30" Power Supply/Voltage DTC cannot be cleared, or reoccurs immediately? How do you know the "30" circuit is not faulty? Just because there is good power to pin 62 at the time you measured the voltage, it is still possible the voltage is not always present, especially when driving the car and vibrations exist that can cause the circuit to drop out. This is why running a new wire with a new terminal at the T121/62 position is my recommendation before replacing the ECU. A new wire from the ECU to the "30" buss connection under the dash, eliminates any possibility of a defect in the circuit. If after running a new wire, the DTC still occurs, then that means the ECU is faulty.

[tekillator]

Okay. I just opened up T121 connector. I have solid good power to pin 62. If not power or ground, then bad ECU?

What was the root cause?
I have the same issue now LOL