B5 Passat TDI - Retrofitting Cruise Control
Introduction
Fitting cruise control is an easy task for the factory. However the access to the place where the connections are made is inaccessible by the time the car is fully assembled. This perhaps why dealers, certainly mine, say retrofitting cruise control can’t be done. There is a reasonably easy way round this impasse, but it requires a “tee” off connection to wires leading to the connection points required for the CCS function. If there is confidence that this task can be performed neatly then the job is straightforward. NB. Being a retired electronics engineer, I have some familiarity with this type of action. If in doubt, either practice away from the car, or find somebody who is comfortable with this type of task.
There are two stages to the retrofitting task. Software and hardware.
1. All TDIs have the necessary software to provide the cruise control function within the ECU.
Normally it is not enabled. How to get it enabled is available from:-
www.geocities.com/MotorCity/Garage/5067/tdiccs/ccs.html
2. Wiring in the cruise control switch is the hardware problem. 5 connection points have to be located.
On my car, a May ’98 model, These 5 points are found at the rear of the ECU. So take the plastic
cover off the ECU box (5 screws, 8mm) which is located under the bonnet and roughly over the
accelerator pedal. Remove the clip that holds the metal ECU box down and move the ECU to one
side. Don’t disconnect it. I saw 5 colour coded 10 way connectors carrying connections to the
passenger compartment. The CCS connections are spread among 3 of these connectors.
2.1 Later in ’98 the CCS wiring must have been tidied up as the connections were moved to a 15 way
connector coloured white. This connector also carries the brake and clutch switch wiring..
2.2 Remove the cover to the fuses, then remove the cover panel that hides the pedal hinge area.
(4 screws and one clip then it can be withdrawn from the clip by the accelerator pedal). Access to
the connectors to properly plug extra wires in is very difficult. Look up by the accelerator pedal
and you will see the problem. Do you want to dismantle the stuff in the way?
2.3 Check the wire colours on the connectors and if they match the information here then the CCS
connection points have been located. If they don’t match then it will be necessary to get access to
the correct current flow diagram for the year/model. As an extra check, try to confirm that there is
no wire leading from the connector as each point is located. I could spot 2 of them missing, so I
was confident that I had got the right points.
2.4 Working from above, in the bottom rear of the plastic ECU box, identify the connector and the
wire. Move back along the wire towards the ECU sufficiently to achieve handling space. Very carefully remove enough insulation to “tee” off a wire to take to the CCS switch. Solder in the “tee” off wire and carefully re-insulate the connection. Repeat this for each connection required.
2.5 Either obtain and fit the proper VW CCS/indicator stalk switch and complete the connections. Or
make up the necessary switch functions and mount them on one of the switch blanks next to the radio. The problem with the VW switch is getting a mating 10 way connector, this connector would normally be a “harness” connector. I used miniature switches, 2 push to make (set and resume) and 2 toggle makes on a switch blank. I used the bigger one to the right of the radio. This solution is also cheap at less the £3.50. The VW switch solution will cost around £100 for the switch plus workshop time (steering wheel off/on).
2.6 10 way connector layout - viewed from ECU side
________
* * | 1 5 | ßcoloured surround
* * * | 2 9 6 |
* * * | 3 10 7 |
* * | 4 8 |
The colour coding is by a squared off “U” shaped surround to a purple contact block, when viewed looking downward from the ECU side
2.7 Connector Pin Wire
Colour Function
T10b Black 8 Red/Yellow Set
T10e Yellow 1 Blue Resume
9 Black/Yellow Enable
8 Red/White +12V
T10d Light Brown 1 Red/Slate On
NB. The white 10 way connector carries the brake and clutch switch wires.
2.8 The VW Cruise Control Switch
2.9 Using 2 Toggle and 2 Push switches
Mount the miniature switches on a switch blank. To do this in a square layout will require a little removal of plastic from the rear of the blank. I chose to have the 2 toggle above the 2 push switches. I also had the “set” switch with a red top and the “resume” one with a black top. I printed out a suitable label, using white on a black ground, for the assembly and glued it to the blank. The switch nuts also help secure the label.
3. The 15 way connector uses the same wire colours for the cruise switch functions as shown above.
The connector is designated T15a and coloured white. It will be in the plastic ECU cover box.
A current flow diagram for the later ’98 model, shows the ECU having an 80 way connector, T80, with 4 pins taken to CCS. The earlier model, mine, has a 68 way connector on the ECU, (plus another smaller connector). The routing is shown through 2 other connectors T15a and T10 on the CCS switch, as follows.
T80/10 to T15a/9 to T10/3 to CCS red/yellow wire Set
T80/21 to T15a/8 to T10/2 to CCS blue wire Resume
T80/35 to T15a/7 to T10/5 to CCS red/slate wire On
T80/19 to T15a/10 black/yellow wire Enable (I assume)
T15a/10 to T10/7 to CCS black/white wire
T15a/10 to T10/4 to CCS black/white wire
Ignition/SW 12V to T10/6 to CCS red/white wire
T15a is also shown carrying the clutch and brake switch wires (T15a/11 to T80/20 red/black T15a/12 to T80/9 red/slate & T15a/13 to T80/46 red/yellow).
NB. Not having this connector on my car this is all I know about this wiring version.
Howard Baker 1st July 2001