skiwi

after a variety of delays, not the least that the car started over-heating (thermostat), i have resumed work on the "tip on demand" upgrade. after testing my circuit and making a variety of modifications to reflect what i found, i now have a fully functioning circuit.

i have had to spend a lot of time on the steering wheel shifters as they are not, as it appears, simple switches. the wiring diagrams here are simply incomplete. the steering wheel tip switches are held open by the tcm sending 12v across them, with a diode preventing feedback. this has the effect of neutering the switches until the tcm recognises "tip mode", where it drops the voltage to a trickle for the diode, but now allowing the switches to be grounded. hence my plan to use them to initiate the circuit required re-thinking. to further complicate matters the "ground" feed from the switches doesn't go to ground at all as indicated by the wiring diagram, but into the steering column, location unknown. i haven't bothered to find out as there is a perfectly good ground in the steering wheel which i intend to use.

for the circuit to work i need to bypass the steering wheel switches from their circuit, i.e. use them as simple switches switching "tip +/-" to ground. as such my circuit works as advertised. i have tested it using vag-com (measuring block 11, transmission module), and in also with a test drive.

1) switch up or down will force "tip" mode and then the gear change, and hold "tip" mode for 5 seconds.
2) using vag-com there is no discernable difference between the manual tip mode and the "tip on demand" mode
3) no codes are logged
4) with the transmission lever in any position other than "d", the tcm ignores the change and logs no codes
5) it is, as i have experienced in other cars, a nice upgrade to the driving experience

i have thought long and hard about the location of the electronics and ditched my initial plan to use the e-box. at it stands now, the electronics are contained in a smallish self-contained box, integrated into the wiring system under the drivers-side (rhs) dash using a 5-pin din plug. 5 wires are required, +, -, tip +, tip -, tip recog. the box is mounted on the rear side of the drivers dash panel where there is enough room for an elegant mounting solution.

for the next stage, i want to move from "prototype" status to version 1, and will re-design the circuit to improve speed (<0.2s lag), ensure the timer re-starts on re-activation, and to reduce the component count and size. i will also re-engineer the tip switches as described above.

once this is done, i will post photos and circuit schematics. the circuits are considerably different from those that i posted last month. i expect to have this completed within the next month.

PaulW

Sounds interesting!

JimR

Excellent! Sounds cool.

Jkay

Good luck! Nice Job!

Always Overcharged

Any use for some number eight wire in there somewhere-lol

skiwi

and i like a challenge. keep the little grey cells stimulated :-)

ttuling

If you get time to post here the actual wiring diagram for the steering wheel buttons, that could be helpful if anybody ever needs to troubleshoot them.

Tom

skiwi

the circuit has 2 boards, a relay board, which i'm not changing, and the timer board, which i am. i'm going to use 556's instead of 555's and reduce the component count somewhat. i will certainly post the diagram once i have it debugged.