cruise control tach wire

Does anyone know where you connect the tach wire to on a diesel sc 1995? It acts as a fIt acts as a fail safe device off you accidentally knock lever out of gear and prevents cc from over revving. All I can find is a ref to connection to black wire of diagnostic plug? Any help out there?

I'm ok with all other connections I have to make just this one im insure about. Ill post all info and pics once installed my rostra cruise control unit.

I have just completed installing a Rostra Cruise Control unit to my 1995 Hiace. to be honest it was easier than installing my radio. took me about 3 hours tops and was very simple. I have taken photos of how and where that I happily share. its working absolutely perfect from my install with no further adjustment needed.
first I installed the black box unit down in between the control to left of my left rest pedal (RH drive car) bolted unit via bracket and two bolds to a galv frame under there. I removed the two clip on side covers to each foot well then four side screws and pulled up the small section of console that is around the auto gear knob and drinks holders.. this gives you great access for the unit, all the wiring and also access to drill bulkhead using a cordless drill. i ran mine tight just to the side of the gear selector as the plastic cover comes in close.
drilled small hole to bulk head 8mm above radiator fan for cable to get into engine bay and cable tied it to sound proofing to keep it away from fan.
then installed the cable end just above the throttle linkage, via a bracket supplied. I used the original cable and nut to secure the bracket in place. then had to add a loop to cable to the add extra length for rostra 41 mm travel required. this loop passes over the bobble on end of throttle cable.
both cables then ride in same cam shoe of the throttle linkage. that's the mechanical bit done.

secondly its all the wiring.
first I bolted the earth to a common earth in passenger footwell/console area where there is a sub fuse board. un-tightened 10 mm bold and added my ring connector to two other originals.
then two connections to the brake switch, one to 12v permanent positive(hot side) which is a green/with red tracer.
then other wire from rostra to cold side.
then VSS wire for pulse rate. My van has a futuristic electronic dash readout and the( vehicle speed sensor) VSS is best connected to feed to the ECU(engine control unit) unit which is located on passenger door post under seat belt. recline front passenger seat forward and then from rear sliding door remove screw holding engine cover retaining strap. Part of the side door seal and lower push in plug also hold this cover so remove these and pull cover off. On my ECU I have three plugs a 26, 16 and a 12 pin plug. the VSS connection is on the 12 pin plug and is the second connection in from the side if plug that mates up to the middle plug and on the lower row, the upper row being the plug clip side. the wire is coloured purple with a white tracer- I connected my rostra wire to this via one of them plastic splice clips, the wrapped back in black wire harness cover , then replaced all covers and trims etc.
I also had to make one connection to a 10 amp fuse which I used the indicator feed that is only live when ignition on, as required.
I also have not connected the tach wire yet as im not sure where it goes and it will work without it. That's all the wiring done except for the control new stalk.
for this I removed the 6 screws and removed the covers from around the steering wheel. undo the two cover plates either side of the steering wheel and loosen the two screws behind. remove the horn fuse. and pull off the horn cover. undo the 19mm nut holding the steering wheel on,and remember wheel position before pulling wheel off, then undo the four screws holding the black stalk assembly on and pull off over the steering wheel shaft. you should then be left with a tin plate showing. I bolted my new stalk to the back of this using one bolt. I then had to cut a slot in the cover to allow for it to pass over stalk. then re-assemble, plug stalk plug into CC harness and that was it all complete. After setting all the Rostra micro switches as per the setting required, I then ran through the Rostra self diagnostic test which it all passed and then took out on a test drive which proved perfect.
the Hiace's use a 4 pulse/mile setting with a square sine wave pattern.
I have tested the unit now on road and its very responsive and holds speed to within 2km. which I find great. cant wait to use it towing where I need to keep 10 km under normal limit. I have some pictures and can take more if required. hope this helps ..cheers Paul

Thanks.
Grateful if there are any photo updates on here (see: https://hiace-super-custom.forumotion.com/t4308-help-locating-the-tach-wire-going-into-digital-dash#24030
Cheers