Rev Counter In A Diesel

[yeti-dj 7]

hello, finally getting round to rebuilding my diesel comutting beast after killing the engine, amazing what a little water can prevent, and have now got a different dash display, the one with the rev counter, i also have all the wiring plugs from the dash.

 

want to get the rev counter working but not sure what i need to do this, can any one help me out?

 

thanks people.

Edited November 12, 2006 by yeti-dj

[DaveW 6]

I think the revcounter runs off the flywheel...

[yeti-dj 7]

have noticed a sensor on the top of the fly wheel but had no idea why the diesel had this as it doesnt have a rev counter in it.

 

could this be what i need or does this do something else on the old derv?

[sonofsam 5]

That sounds like the TDC sensor.

I *think* to run a rev counter you may need a gearbox speed sensor with an electronic connection?

[Anthony 1,003]

On the old 1.7/1.9 TD engines the rev counter is driven from the flywheel sensor

[yeti-dj 7]

So is it just a case that i get one of these sensors and fit it then wire it to the dash board. Any idea where it is on the engine/gearbox?

 

 

Would i also need the flywheel or is the one thats on going to be ok?

 

The engine is from an L-plate 1.8 t diesel.

 

thanks for the help

[pug_ham 245 3 Cars]

I think that an L reg diesel will already have the sensor fitted in the right place.

 

Its the usual odd spare brown plug that sits on top of the rocker cover. They have to be set at a specific distance from the flywheel to read correctly & if you haven't got one its a gearbox off to do it right.

 

You'll have to fit the rest of the wiring though as on a diesel it isn't a single wire.

 

Graham.

[PumaRacing 2]

Before flywheel sensors came along, diesels used to take their tachometer signal off the alternator. Obviously the alternator and crankshaft don't necessarily go at the same speed so the system had to know the pulley ratio between the two.

[welshpug 1,677]

I think that an L reg diesel will already have the sensor fitted in the right place.

 

Its the usual odd spare brown plug that sits on top of the rocker cover. They have to be set at a specific distance from the flywheel to read correctly & if you haven't got one its a gearbox off to do it right.

 

You'll have to fit the rest of the wiring though as on a diesel it isn't a single wire.

 

Graham.

 

 

if it needs a TDC sensor fitting, and you're using an old sensor, place it in the hole as far as it will go then withdraw 1mm, If youre fitting a new sensor it has 1mm long tabs on its end that wear off so just bolt it right in there.

[yeti-dj 7]

there is already a sensor on the top of the gearbox that has a brown plug on the end of it but this is pluged into the wiring already. So this must be the TDC sensor right?

 

Forgive me for being daft but why on the diesel is this TDC sensor needed as there is nothing for it to tell when the engine is at TDC or am i missing something?

 

not too good at diesels as you may have guessed already..

 

cheers again

[welshpug 1,677]

TDC sensor needed as there is nothing for it to tell when the engine is at TDC

 

 

as in on petrol engines theres electrical pulses that are picked up on, which are translated into RPM signals, obviously on diesels, particularly mechanical ones there arent any electrical pulses created by the engine, hence the need for a sensor, or as some work they pick up from the alternator.

[yeti-dj 7]

thats the thing though, there is a TDC sensor there but the car has no RPM counter in it at the moment so whats it for or is just being unused at the moment.

 

But surely as this is plugged into the cars loom this would suggest that the wiring for the RPM counter is already in place in the car or would this be too easy?

 

cheers..

[yeti-dj 7]

hello, just having a look through my haynes manual and cant find out how to wire up the TDC sensor to the new dash board to get the rev counter working.

 

can any one help me out in how i do this or if you have got a wiring diagram that makes some sense.

 

thanks again......

[Richie-Van-GTi 74 2 Cars]

the tdc sensor only kicjks out about 3-5v max, most rev counters need a minimum of 10v on the signal pulse. I had issues trying to get one to work before. In the end I found out the alternator pulses 16 times to fast for the rev counter but you can buy a chip that will only allow one pulse every 16 so that you get the correct pulses per revolution for the tachometer. This is assuming the tacho works on the same amopunt of pulses as the one I was using which was an autometer one. Im guessing you are using standard pug gauges?

If it helps any 306 manuial will have the wiring schematic that shows how the TDC sensor is wired for TD tachometers.

[yeti-dj 7]

cheers for the help, guess i will just rip it all apart and see what i can come up with. cant be that hard can it?

[Guest BrainFluid]

1: Get hold of a 205Td's instrument read out box thingy (a bionical? is that the right word?).

 

2: Put that into your car (make sure you disconnect the speedo cable from the transmission first or you will break it when you pull bionical out)

 

3: Plug your loom into the gearbox Rev Sensor.

 

4: Hey presto, it'll probably work , sounds to me like all the wiring is already set up mate.

 

Hth.

Edited November 14, 2006 by BrainFluid

[sonofsam 5]

Bio this, Bio that..

 

Its Binical Bro:D

[Guest BrainFluid]

Its Binical Bro:D

 

Excellent, thanks man. That was preparing to bug the crap out of me!

 

Still hanging ten then

[yeti-dj 7]

next problem is that all the plugs on the back of the instrument display are different so will need to cut and shut the loom anyway.

 

But the next problem is that the TDC sensor is plugged into the loom in the engine bay but where does this go as the car doesnt have a rev counter fitted or every has had one.

 

good old peugeot wiring eh......

[Guest BrainFluid]

Really? Are you 100% sure that the plugs that plug into the binical are different to the ones on a Td?

[yeti-dj 7]

sure am, the turbo diesel with a rev counter also has many other guages like water temp and low level oil lights but the dash in my turbo diesel is super basic, have only got speed and fuel guage and some warning lights oh and a really pants clock. The back of the dash with the rev counter likes very like my 205 GTI dash.

 

With this in mind looked in the haynes manual and found a wiring guide for the dash with engines XV8,XW7,XY8 and XU51C with this be the same as the diesel and its an XU engine???

 

cheers people....

[Guest BrainFluid]

Sure, but I think that you will find that the plugs that fit from the loom into the back of the binical are the same kind of plugs on both the petrol and diesel.

 

I also think that you will discover that behind your binical there will be spare plugs that will plug into a turbo diesel binical.

 

This is why I say that if you just get hold of a Td bincal and plug it all in at the back I think you will be surprised to find it all works fine and dandy.

 

 

I am a little confused as to why your Gti thats been converted to diesel has a base modle binical.

[yeti-dj 7]

ok, wasnt clear to start with this is a 5 door 205 turbo diesel that i am working on and i think its a GRD or something.

 

have take out the dash display and none of the plugs are the same at all so will need to chop up the loom, the wiring in the car is very basic where as the wiring from the donar car with the rev counter has lots of wiring for the ECU etc so looks to be very similar to the GTI,pants.....

 

have been checking out the rev counter in the dash display and it just works off of one wire so shouldnt be too hard to figure out i hope.

 

cheers for the help people.