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Discussion Starter #1 (Edited)
Cleared all codes... drove a bit... got some codes. The only one I don't know what to do with is
P175000. The car is a 2004 B5.5 Wagon ATQ V6 Automatic. The code is from the Transmission Control Module and P175000 means Voltage supply: too low. What does it mean? What to do about it? Note: I did replace the alternator, and yes, all gears were highlighted in the dash..

I saw FrescoGreen01.5's response in 18158 - Supply Voltage P1750 - 003 - too low So is that a place to start? It does seem like my terminal 26 isn't getting power in the TCM
 

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I guess you mean P1750 or 18158.
FrescoGreen01.5's suggestion looks like a good place to start.
 

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Cleared all codes... drove a bit... got some codes. The only one I don't know what to do with is
P175000. The car is a 2004 B5.5 Wagon ATQ V6 Automatic. The code is from the Transmission Control Module and P175000 means Voltage supply: too low. What does it mean? What to do about it? Note: I did replace the alternator, and yes, all gears were highlighted in the dash..

I saw FrescoGreen01.5's response in 18158 - Supply Voltage P1750 - 003 - too low So is that a place to start? It does seem like my terminal 26 isn't getting power in the TCM
Yes, a good place to start. Check the power on both sides of the fuse first. If you have 12v on both sides of fuse #15, then find out where the problem is between there and the TCM. It looks like the red/blue wire from Fuse #15 is spliced into the red wire on terminal 26 of the TCM plug. Could be a corroded splice.
 

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Discussion Starter #4
Well, I took apart the TCM, whose case was bone dry, btw:

99928


Then I checked out the connection on pin 26 and it seemed fine:

99929


The other side seemed a bit corroded, so I used some 400 wet/dry to clean them up:

99930


99931


There was just a bunch of old car smegma (LOVE that word) around the seal (so was there water in there at some point? ) so I brushed it out.
99932


I noticed a bunch of buildup on the teeth of the TCM itself, so I cleaned them up:

99933


99934


The wires outside of the box don’t look happy.
99935


When I checked #26 with a meter, the most volts I saw was .15v with the car off. Q1: What should the actual resting voltage be? Always 12v? Sorry, I didn’t check at the fuse yet; only that the fuse was functional. After putting things together, but not back under the mat yet, I cleared the codes, but when I reset and tried again, the same code was back. Q2: where abouts is the splice into the single red wire?
 

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Discussion Starter #5
Oh, BTW, I have unlimited VINs and have the ability to bleed the ABS controller, and many many VAGCOM functions for only $145 CAD:

The Ancel VD700

99937


yay!
 

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Well, I took apart the TCM, whose case was bone dry, btw:

View attachment 99928

Then I checked out the connection on pin 26 and it seemed fine:

View attachment 99929

The other side seemed a bit corroded, so I used some 400 wet/dry to clean them up:

View attachment 99930

View attachment 99931

There was just a bunch of old car smegma (LOVE that word) around the seal (so was there water in there at some point? ) so I brushed it out.
View attachment 99932

I noticed a bunch of buildup on the teeth of the TCM itself, so I cleaned them up:

View attachment 99933

View attachment 99934

The wires outside of the box don’t look happy.
View attachment 99935

When I checked #26 with a meter, the most volts I saw was .15v with the car off. Q1: What should the actual resting voltage be? Always 12v? Sorry, I didn’t check at the fuse yet; only that the fuse was functional. After putting things together, but not back under the mat yet, I cleared the codes, but when I reset and tried again, the same code was back. Q2: where abouts is the splice into the single red wire?
Following this.
I have the exact same issue. The wires look crudy. I am planning on replacing the entire wiring by removing the carpet and soldering if necessary.


Sent from my iPhone using Tapatalk
 

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the wires do have splices (have a really good light source) they are 'welded" not soldered, and to find them you have to remove the black cloth tape, I am going to include in this post the wiring diagram which will allow you to check at the harness "bonnet" that plugs into the TCM all the way thru to the transmission "internals, I prefer doing this as then you can decipher if any of the wires have problems between the TCM and internals of the transmission. Personally I would first check and clean the ground wire (always a brown wire) for the TCM which is at the passenger side "A" pillar and any of the TCM plug in connectors also there. As a side note you have to be careful cleaning connectors as you can remove their corrosive resistant plating. You may have had water/moisture in there but probably dried out since car has been garaged for a while. I will send documents as to solenoid OHM readings if needed.(included, any questions PM me) As a point of interest as you seem like a curious soul , the TCM wiring goes two directions, with some wires going to pass. side "A" pillar the others go towards the rear of pass. seat then continue over the "high" point of the chassis pan to the complimentary side of the rear of the drivers seat, they then pass along the driver's footwell to the cars firewall. From there they work their way down the fender well to the front of the 0V1 5HP19 transmission. There are two major connections one is to the "range" multifunction switch also known as the PND switch, and two, the rotational interlock that goes to the transmission's internal sensors and solenoids. Both are suspect to connections as the are exposed directly to the elements. Take out pass side seat if not done, makes life so much easier.
 

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Discussion Starter #9
That red wire should be between 12 & 13 Volts with engine not running. (Same as at fuse #15)
I suggest you unwrap the harness until you find the splice.
Does anyone have an idea where that splice might be? If not, I'll post pictures and map out the location for anyone's perusal...
 

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Looking at Bentley schematic 41/3, the splice (A1) is in the instrument panel wiring harness. The wire it splices to goes to the Selector Lever Light Relay, position 6 on the 13-position relay panel, relay 205. Therefore, I'd venture that it's in the vicinity of the relays or fuses. It's up out of the wet, so it doesn't seem the most likely culprit.

Fuse 15 is hot all the time. The load-side wire runs from the fuse, through the splice, to the brown connector at the right A-pillar (pin 11), to the TCM connector. It changes color from red/blue to red at the A-pillar connector.

Side note: schematic 50, which applies to the AWM (1.8T) engine only, says the relay was deleted after April 2003. It seems odd that only on the AWM--I wonder if you have the relay (and splice) at all.
 

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you have got to remove seat to have viable access to the wiring,have you checked the gound fo the TCM at the base of the pass. side "A" pillar? The PDF in post #7 in my opinion is "gold" when sorting out the TCM wiring.
 

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The wire from fuse #15 is Blue/Red, it joins to a Red/Blue wire (probably in the dash),
and then it joins to a Red wire (probably at the "A" pillar). That Red wire connects to the TCM.
I suggest you check the connector at the "A" panel.
It appears that there is no splice in the TCM harness on the floor.
See post #10.
 

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Discussion Starter #13 (Edited)
Great stuff. FYI, my car’s manufacturing date is in December 2003. (It’s sold as a 2004) I’ll be into this tonight/this weekend. Tuesday, my new NKG ignition coil and wires arrive (along with a new aerial whip mast antenna, and CV boot), so I want to be ready for then - because then I can drive to get the sorely needed antiroll bar bushings and connector links.... almost graduation day...
 

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Discussion Starter #14
I don’t think a splice is the issue.

I followed the thinner red lead from pin #26. I thought it was the thicker one and wasn’t 100% so I opened the harness plug again. It’s the thinner red wire.

99975


Then I unravelled a lot of hockey tape... was the harness made in Canada? You can see the thin red wire loops back and goes towards the dash.



99976


I followed that up to the plug it goes to; the lower mustard coloured one closest to the passenger door:

99977


Well, I unplugged that to have a look, and I think I found my problem:

99978


and the socket is similar. There’s a ton of corrosion in there. Humidity? The car wasn’t ever in the river... Humidity after 16 years might. I’ll clean this up, or replace, and see if this fixes things...
 

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That plug looks pretty bad, I think it would be a good idea to replace that plug and socket.
You could get them with tails from a junk yard and splice them in.
Pretty sure that is not from humidity, I suspect there has been a leak, maybe from sunroof drain.
 

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Discussion Starter #16 (Edited)
Ok. If I can’t clean it up, that’s what I’ll do. The red wire goes to the 4th pin, and on the socket side, that’s the fabled blue/red wire :

99979
 

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Ok. If I can’t clean it up, that’s what I’ll do. The red wire goes to the 4th pin, and on the plug side, that’s the fabled blue/red wire :
That is the Red/Blue Wire (Red with Blue tracer), The Blue/Red wire goes from the other end of that wire to Fuse #15.
 

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Discussion Starter #18 (Edited)
Well that was the wire that was in the pin location for the red wire. I’ll examine closer later and rotate the wire a bit to clarify. I also better check my orientation of the plug to make sure I don’t have the pin order reversed!
 

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Good work, that hockey tape really brings out your fingerprints. Despite pulling two entire dash harnesses for my swap, I don't envy anyone doing this electrical work.
I've considered pulling the TCM harness out of the body harness, but that would be even more work.
 
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