Running/Driving - but 20 faults: ECT short+, and All 6 Cyl's ignition open circuit

OP, you say "So these 5 codes remain constant"--which ones do you refer to?

A lot of your codes seem to point to ground wire issues, as if some of the ECM ground wires are missing or poorly connected. Assuming the 2.7TT ECM is of similar design to the Passat ECMs, the ECM generally switches the ground side of ECM outputs, not the plus side. A missing ground connection will cause it to see 12 volts when it turns the transistor on (rather than 0 volts) (through the solenoid coil, etc), which will give you the "open or short to plus" code. The ECM grounds (several of them) are on a stud on the firewall in front of the ECM.

You also need a good ground connection between the engine and body, since the battery ground connection goes to the body. I presume there's a ground strap, since the motor mounts wouldn't conduct, but I don't know exactly where it should be.

Regarding your SAIP fuse--likely the SAIP has filled with water (from combi valve not closing) and corroded such that the pump (fan) can't turn.

The EPC light is essentially a "limp mode" indication, indicating that the ECM doesn't have at least one important input, so it's not going to let you be aggressive.

The "5 codes remain constant" comment refers to the 2 dashlight (k83/EPC) codes, the Crash signal, and the O2 sensor codes from being unhooked.
I've now plugged in the rear O2's and those 2 codes are now erased. So there are a constant '3' now: K83 light, EPC light, and Crash signal
I've also erased the miss on cylinder one, the brand new coil is working for the time being (the other 2 used ones only lasted a day).. I've heard of conditions where an igniter or icm or some other cause will eat through ignition coils left and right - I guess I can wait to see if replacement #3 goes bad to address this, but... just concerned
also, I mentioned O2 sensor readings for bank1 sensor1 were bouncing around - voltage from .02 - .72 and correction values from -6% to +10%? - is this normal for them to bounce around/constantly adjust/correct? if so, what are the parameters/specs to watch for? Now Bank2 Sensor1 is constantly reading No Activity or Open Circuit.. so I'll be replacing that this week.. but wanted to confirm what I should be looking for in a working sensor, and if Bank1 Sensor1 fits that scope
I've double checked the Grounds at the firewall, and the ground strap next to the passenger motor mount - all SEEMS ok there..
There seems to be a few more ground locations, didn't get into them much.. I'm hoping to get a little more insight or direction as to which locations I should be poking around at..

So, now that I've rid a few of the codes - I'm stuck with the "constant 3" of course (ignoring for now), and Then comes the ECT open circuit, and ECT signal too high:

5 Faults Found:

17931 - Crash Signal from Airbag Controller
P1523 - 35-00 - Implausible Signal
18098 - Malfunction Indication Light (K83)
P1690 - 35-00 - Electrical Malfunction
18084 - EPC Warning Lamp (K132) Circuit
P1676 - 35-00 - Electrical Malfunction
16502 - Engine Coolant Temp. Sensor (G62)
P0118 - 35-00 - Signal too High
18028 - Engine Coolant Temp Signal
P1620 - 35-00 - Open or Short to Plus

I get the open or short code immediately after I clear them out - comes right back. Again, I've replaced the sensor, so I'm leaning towards bad wiring or ground, but I'm curious if there is a module, maf, icm, relay, etc within the ECT circuit that could be shorting the ECT? I've heard of the ECT causing some pretty unsavory symptoms - Does it share a circuit with all 6 ignition coils? would any of the modules, maf, icm, relays, etc be linked to the 6coils? Would any of them share both ECT / 6coils in their circuit? Is there a grounding point where they are linked? or should I look into the ECT and 6coil codes separately?

So, I clear the codes. First get ECT code. Clear, ECT. Clear, ECT... so then I start the car; ECT of course, The "constant 3" (ignore), and bank2S1 open circuit:

6 Faults Found:

17931 - Crash Signal from Airbag Controller
P1523 - 35-00 - Implausible Signal
18098 - Malfunction Indication Light (K83)
P1690 - 35-00 - Electrical Malfunction
18084 - EPC Warning Lamp (K132) Circuit
P1676 - 35-00 - Electrical Malfunction
16502 - Engine Coolant Temp. Sensor (G62)
P0118 - 35-00 - Signal too High
18028 - Engine Coolant Temp Signal
P1620 - 35-00 - Open or Short to Plus
17528 - Oxygen (Lambda) Sensor Heating; B2 S1
P1120 - 35-00 - Open Circuit

It will Idle and continue to spit out these 6 codes constantly. Hit the gas, and then I get all 6 cylinders short to plus:

12 Faults Found:

17931 - Crash Signal from Airbag Controller
P1523 - 35-00 - Implausible Signal
18098 - Malfunction Indication Light (K83)
P1690 - 35-00 - Electrical Malfunction
18084 - EPC Warning Lamp (K132) Circuit
P1676 - 35-00 - Electrical Malfunction
16502 - Engine Coolant Temp. Sensor (G62)
P0118 - 35-00 - Signal too High
18028 - Engine Coolant Temp Signal
P1620 - 35-00 - Open or Short to Plus
17528 - Oxygen (Lambda) Sensor Heating; B2 S1
P1120 - 35-00 - Open Circuit
17763 - Cylinder 1 Ignition Circuit
P1355 - 35-00 - Open Circuit
17772 - Cylinder 4 Ignition Circuit
P1364 - 35-00 - Open Circuit
17769 - Cylinder 3 Ignition Circuit
P1361 - 35-00 - Open Circuit
17778 - Cylinder 6 Ignition Circuit
P1370 - 35-00 - Open Circuit
17766 - Cylinder 2 Ignition Circuit
P1358 - 35-00 - Open Circuit
17775 - Cylinder 5 Ignition Circuit
P1367 - 35-00 - Open Circuit

I can produce these results time and again: ECT with just ignition on; Constant 3 and O2 B2S1 once started; and all 6 cylinders open/short to plus once I hit the gas. Why do all 6-cyl's short when I hit the gas? how is that related? FP.Relay? ICM? ....ECT??...

I'd like to replace the O2 sensor immediately to get it out of the equation; same with adding LED's to clear up K83 and EPC light malfunctions.. I'm especially curious if I'm stuck with this Crash Signal code forever.... but right now - Why is my ECT shorting out, along with all 6 coils??

Lastly - once the codes are cleared up, do I have to clear the EPC light manually/VAG? or will it go away on its own? is there a way to scan for WHY the EPC is on??

BTW, Thank you for your help. Much appreciated

Ok...
I plugged a new O2 sensor into bank2S1 - so far so good. No O2 codes coming back.
Triple checked grounds.
Cut away shielding on wiring harness from ECU to the airbox and inspected wiring. Everything looks nice &shiny. no breaks that I can see...
Checked wiring at ECT plug - electrical taped between all 4 wires in case there were hairline cracks arcing.. The ECT signal too high has not come back yet.


Still getting ECT open circuit immediately after clearing codes.
Still getting all 6 cylinders Ignition Open Circuit if I hit the gas

So... Do you think I should find the ECT's wiring diagram and just ground it to the chassis?
Same with each coil? Is the ICM supposed to be grounded, or is that just a heat sink? ..grounded through the plug/harness..?
Does anyone have, and/or care to share these diagrams?

So... You really don't think that ALL 6 CYL's Ignition having an Open Circuit would have anything to do with ICM, MAF, ECU.Relay, or FP.Relay??... what #should be on the relay in the E-Box? 214? 373?
And is the ECT linked to any of them as well?? Does the MAF read ECT and also send signal to ICM or All6 coils? Doesn't the FPR link to the Ignition circuit?
When diagnosing, aren't you supposed to start with simple stuff like checking connections, fuses, relays, upstream components? Or should I really start by just ripping into the harness on a wire hunt... PLEASE - any direction would be appreciated!!

I'm not great with diagnostics, or a Multi-meter, but I have one. Anyone care to guide me through some basic checks/tests so I can narrow down where the issue is coming from?

Hey guys. Looking for a little diagnostic help. Just finished swapping a 2.7t into a '00 Passat 4motion. The car runs and drives ok, but I've got the EPC light on, and some codes:

1. Engine Coolant Temp Sensor - Short to Plus
This code comes up with only the ignition on, not running. I clear the code, comes right back. I replaced the sensor, and wired in a new pigtail - still comes right back.
Is this possibly due to any differences between the 2.7t and b5 chassis? Like maybe because of differences in clusters, or maybe because of pinouts not matching where the engine harness plugs into the dash harness in the E-box? Does anyone have the wiring diagrams or pinouts for both 2.7t ('00 A6 tip) and '00 Passat 2.8L 4motion tip? Or is this likely just a glitch in wiring harness - broken or frayed wiring? Any tips or step by step to trace the issue?

2. When the ignition is on, only code is the above ECT short. When I start the car, I get 3 more: Crash Signal, EPC light circuit, and K83 light circuit. I'm wondering with these, too, if it would have anything to do with different clusters or pinouts in the E-box? I read somewhere that someone got rid of the 2 light codes by splicing in secondary LED lights and it fixed it - still need wiring diagrams or pinout to complete this. Crash Signal, I guess you cant get rid of..? Anyway, So ignition on: ECT short. Start the car: Crash Signal, 2 indicator lights. When I hit the gas...................................

3. Cylinder (1,2,3,4,5,6) Ignition Circuit - Open Circuit
Why ??? First, I've heard of the ECT causing some strange issues, so would this relate to the ECT short AT ALL? Why would the car start or even run if all 6 cyl's have an open circuit? So does that mean that this is a short "blip" where all 6 cyl's lose GROUND once the throttle is tapped? Is this related to the throttle or DBW, Pedal at all? Is this a SYMPTOM of the EPC light being on - does the function of the limp mode cut signal to all 6 ignition circuits? I'm kinda lost on this one. Am hoping its either a replaceable part such as MAF, ICM, FP Relay (is there an Engine Power Control Relay that I should be looking into at all?)... Would it be as simple as running individual grounds to each coilpack and grounding to chassis?? The car will idle all day long without throwing these codes, but as soon as I tap the throttle - all 6 cyl's Ignition Open Circuit....

Bought myself a new Multi-Meter, and ready for input!!! Need pinouts and some step-by-step diagnostics.. Please.
Thanks in advance. Pics and build thread coming soon.

From another thread where swapping the 2.7t into B6:
I don't exactly understand, but maybe someone here can help to elaborate, or just tell me what to do

From what I understand and have gathered the last 12 hours of researching all these faults I have are due to the wires from the ECM not having any where to go.

"Coolant temperature signal
The engine control unit receives from the dash
panel insert a coolant temperature signal
calculated from the signal which coolant
temperature sender G2 generates and a
related temperature characteristic.
The signal is a “data message“ and is
connected to the earth potential when a
temperature of approx. 120 °C is exceeded.
In this case, the air conditioner’s operating and
display unit switches the compressor off along
the bidirectional wire designated “Airconditioner compressor On/Off“.
As of a temperature of 116 °C, the charge
pressure is reduced in order to counteract a
further rise in temperature.
If the temperature drops below a value of
approx. 116 °C, a data message is again
transferred and all actions previously
performed are reversed."

This is what I got from the 2.7t self-study. This one wire for fault 18028 which is the temperature coolant temp signal is bi-directional and gets a message from the cluster. With it not wired it it's an open circuit. Same for 18084 and 18098.

The above post talks about 3 of the 5 codes I have:

1. 18028 ECT open to short
2. 18084 EPC warning lamp signal (k132)
3. 18098 Malfunction Indication light (K83)

Says They're all "bi-directional" meaning they send and receive signal from the cluster, and guess what I found....

5 wires where the engine harness meets the body harness. everything matches up identical except the 2.7t harness has these 5 extra wires that aren't even pinned in the 2.8Passat's body harness receiver. The locations are:

ORANGE CONNECTOR: pin#3-Red/Yel; pin#9-Brown/Red; pin#10-Blu/Red
TAN CONNECTOR: pin#5-Blk/Blu; pin#6-Wht/Blk

Are these possibly the ECT, EPC, and MIL signals that I'm NOT getting????????
But where do they go?... How do I splice them into the Passat?..
The a6 2.7t instrument cluster has an additional 3rd plug in the center that the 2.8Passat does not (it only has 2 plugs - one on each side of the cluster)....
Would I need to splice these 5 wires into that plug and swap over to the a6 instrument cluster? does anyone PLEASE have the A6 2.7T engine to body harness pinouts? How about the cluster pinouts?

My forehead is getting very sore from :banghead:

Orange plug, pin#10, blu/pur - over temp warning signal

Would this cause the code for open/short to ECT?

Orange plug, pin#9, bwn/red - afterrun pump
Orange plug, pin#3, red/yel - afterrun pump

Would THESE cause the code for open/short to ECT?

Orange plug, pin#2, red/bwn - EPC warning light

I'll go ahead and assume this is the wire I need to tap into to add the LED.. anyone know how to wire it? Do I cut the wire, put a contact from LED on both sides of cut wire and run it in-line? or do I peel the insulation of the wire some, put one contact from led on wire and other contact to chassis?