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Discussion Starter · #1 ·
Hi - i'm trying to find the alarm control module from a 1998 B5 Passat. I removed the knee plate and looked up in that spot, but i can't seem to find it by the fuse or relay area. Is there a different spot to look for the original 1998 B5?

Car is a 1998 B5 Passat - 1.8T GLS
 

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I'm not sure but I think the alarm control is part of the CCM (comfort control module) which is located under the carpet on the left hand side front carpet (driver side in US).
 

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Discussion Starter · #3 ·
I'm not sure but I think the alarm control is part of the CCM (comfort control module) which is located under the carpet on the left hand side front carpet (driver side in US).
Darn that was what I was afraid of hearing.

The alarm randomly goes off when the vehicle is locked and the system is armed. I have a friend with a diag cable and VCDS that will help me scan the modules this weekend. I'm assuming one of the door lock module microswitches are bad, or intermittently failing. I wouldn't be too surprised if there is also a wiring fault. Getting to the lock module is a pain.

I was hoping to just disable the alarm with out disconnecting the CCM since that controls the power windows, sun roof and power locks, among other things.
 

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On my other vehicle I resolved random alarms by jumpering the hood latch switch so that the alarm system thought the hood was always open thus preventing the alarm from ever arming.
Perhaps you can do something like this with your Passat? Fool the system so that the alarm never arms.
 

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Discussion Starter · #6 ·
Lift up the carpet and remove the CCM. Check for any signs of water intrusion, especially the connector pins and sockets. These cars are notorious for water logging the CCMs and causing all sorts of weird issues.
Yep, we bought this car used in 2000. Originally the CCM was sitting in a pool of water due to a blockage of the drains in the battery area. Those drains are clear. I'll take a look at the CCM and it's wiring later today. The wiring looked fine in 2000 after drying it out and getting a replacement CCM.

I'll get my buddy to scan the car with the diag cable and VCDS this weekend - I'm just hoping it's a faulty microswitch in a door lock module and not the CCM/ or its wiring harness.

Alternatively, can I just wire up a 15A rated switch in-line with fuse #38? I think that is attached to the CCM too. We'll just switch it to the off position when the car is parked, then manually lock the door. ... and turn it back "on" when the car is occupied and want to use the CCM functions (power windows, lights, etc).
 

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Discussion Starter · #7 ·
On my other vehicle I resolved random alarms by jumpering the hood latch switch so that the alarm system thought the hood was always open thus preventing the alarm from ever arming.
Perhaps you can do something like this with your Passat? Fool the system so that the alarm never arms.
Not a bad idea! At least central locking with the remote will continue to work and i don't have to muck around with much more. I'll have a look later. I haven't tried arming the car with the hood open yet (ever).. if that prevents it from arming, I'll disconnect the hood switch contacts and leave it open.
 

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Discussion Starter · #8 ·
Not a bad idea! At least central locking with the remote will continue to work and i don't have to muck around with much more. I'll have a look later. I haven't tried arming the car with the hood open yet (ever).. if that prevents it from arming, I'll disconnect the hood switch contacts and leave it open.

Update on that idea: this 1998 B5 hood latch is purely mechanical - with the hood open, the alarm system can still arm / disarm. No dice.
 

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I wasn’t suggesting that the hood latch switch trick would work for you, but rather using this as an idea to see if there is some other way to fool the system to never arm the alarm system. Perhaps by either jumpering or disconnecting a door switch? I’m just brainstorming here with you.
 

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11 JSW TDI • 09 B6 2.0 TSI • 03 B5.5 2.8 4Motion • 07 MINI COOPER S, "The Chili Pepper"
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The first Passat I owned (a 99, V6 5 speed sedan) had major issues with water. Bought the car with several gallons of water in it underneath the carpet. CCM was a mess, wiring in the harness running along the drivers side was shorted out. Pulled the carpet up, cleaned everything, pulled the cover off the CCM and dried it, and probably did some other stuff to it to aid the operation....but it was quite a number of years ago and haven't had one apart since. That solved most of the issues, though.

Good luck with it.
 

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Discussion Starter · #11 ·
Just a quick update -

I obtained an aftermarket VAG-COM cable with VCDS-Lite and after some futzing around with it, i got it working enough to scan the CCM error codes -- the errors were pointing to the rear left door lock module with an intermittent state. New door lock module ordered from partsgeek.com - it arrived yesterday.



Disassembled the door and checked out the wiring harness - lots of broken sheathing around the door hinge area. I got that temporarily fixed up with Kapton tape while i wait for proper pin extraction tools to arrive.

Funny thing is - the rear left door lock module hasn't worked properly since we got the car in Jan 2020. I tried replacing it with a junk yard pull as well and it didn't work either. I didn't think to check the wiring harness at that time since i wasn't aware of the wire sheathing issues that happen on the VW line of cars.

Anyway, i removed inside decorative panel, disconnected the glass from the window regulator and removed the interior metal cover - checked out the rest of the wiring harness with the DMM - good continuity from connector-to-connector for each of the wires internal.

Removed the door lock module - that thing is wet (as I would expect it to be since it's not in a sealed location). Plugged in the new door lock module and put it on the seat - the system arms/disarms properly and the lock actuator opens/closes.

Went back into VCDS-Lite, cleared the codes and armed the system with the FOB. No random alarms with the car over the past 24 hours.

*A few notes:
  • I have a real Ross Tech cable on order. The aftermarket VAG-COM cable times out a lot. It'll be here next week
  • I was going to install the new door lock module, but the small plastic "wing" that holds the metal rod for the internal door lock is broken. Partsgeek is sending me another one.
  • Pin extraction tools will arrive Saturday. I'll remove each pin from the door to car body wiring harness and use heatshrink tubing over the broken sheathing.

Looks like this issue will get solved.
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Discussion Starter · #13 ·
Fantastic news! Thanks for the follow up.
I'll provide more updates when the parts arrive. It's been a journey with this car.
I'm not a mechanic -- I'm an electrical engineer - I design networking equipment (board / schematic level) for a living.

With that said - this car originally had CCM troubles - When we first got it, the inside was flooded with the dreaded drains under the battery and brake booster - so the inside of the car has been disassembled, seats and flooring have been deep cleaned.

It also had a rough idle (turned out to be a bad MAF, broken crank case elbow).

Then a bad ICM nearly two years later. I only came to the ICM conclusion after the OBDII tools said it was a cylinder misfire -- replacing the spark plug for that cylinder didn't do anything, nor did swapping around the coil packs.I pulled the fuel rail and the fuel injectors and had the injectors tested / cleaned. I learned alot while doing that.

It's a great feeling when you are able to get stuff fixed -- and the support from the folks of this forum is certainly helpful!
 

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Thanks for the follow-up and nice job on the repair. I'd say almost any car is fixable now-a-days with all the information available on the web. I think the B5.5 Passat has such amazing forum support since it is a car that is worth fixing. Just MHO.
 

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Thanks for the follow-up and nice job on the repair. I'd say almost any car is fixable now-a-days with all the information available on the web. I think the B5.5 Passat has such amazing forum support since it is a car that is worth fixing. Just MHO.
A car that is worth fixing, indeed. I miss my C4 Avant terribly. The JSW replacement is actually not much of a replacement at all....but damn, do I love the savings on fuel cost.
 

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Discussion Starter · #16 · (Edited)
I definitely like the car -- but it's a love-hate relationship at times. :)

So quick update: the car alarm went off about an hour ago. I spent a few minutes and scanned the CCM fault codes - nothing registered there --> At least the door lock module is happy!

I'm waiting for the real ross tech cable so i can do a full system scan since the cheapo aftermarket cable times out on most modules.

I'll pull the carpet up and check the CCM wiring harness this weekend - local weather forecast says its going to be dry!

I'm fairly sure I can cut the door latch microswitch wire and still have the central locking do its lock/unlock on all the doors. It'll just prevent the alarm system from arming. That's my "last resort" alternative.
 

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Discussion Starter · #17 ·
For future reference and maybe it'll help someone else down the line:

The "door latch" switch (shown in the picture below with the red and blue wires). The switch is held in pace with a (silver) retention clip. The switch is normally open - e.g when the switch is not pressed, the two terminals have no contact. When the switch is pressed in, the car thinks the door is closed. When the switch is released, the car thinks the door is open.

Since the alarm has gone off today (twice now!). Nothing has been captured in the CCM fault codes.
Right now I've left the mechanical latch open (and thus the switch is not pushed) to see if the alarm goes off.

With the mechanical latch open, the door locking/unlocking still works for this door, but the alarm system doesn't arm (the car doesn't honk when you lock it with the FOB). More importantly, the interior lights turn off when I lock the car with the FOB.

If the car alarm doesn't go off in the next 24-48 hours, I think I'll either cut the wires and solder and heatshrink wrap them together and seal it with grease, or I take apart the door latch module, disconnect the switch and solder a bridge across the two PCB terminals.

  • The first option is easier. Cutting the wires in the middle means i can undo this later with solder and heat shrink tubing.
  • The second option comes with risk of breaking the door latch module but it's cleaner and I don't have to worry about water penetrating. I've taken the original door lock module apart before. It's ~5 screws to disconnect the mechanical/electrical portions and a few more screws to expose the simple PCB (picture of the inside from Feb 2020 for reference at the end). The module has two switches and a motor to actuate the lock/unlock

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Discussion Starter · #18 ·
Huh. Car alarm went off 3 times in succession this evening. The door was left in the same state as noted in my previous post. No wires were cut.

I searched the forum, looks like there are some bits in central elec and comfort control that I might be able to disable the alarm.

Can someone with a B5 Passat confirm this?
does EVERY CCM have the capability of coding an alarm present / not present?
 

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Discussion Starter · #19 ·
New door lock module is installed. Lock/unlock works as expected.
CCM is absolutely dry. No water inside or in the foot well. No corrosion on wires or harness connectors.

I just ended up disconnecting the alarm horn in the trunk for now.

When I get the cable, i'll check out the CCM and Central Elec modules to see what i can do about the horn/lights. If the alarm goes off, i'll have both the horn and flashers disabled so it won't drain the battery.

Cheers!

-Thomas
 
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