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| Combi Meter RPM signal http://www.gt4dc.co.uk/forum/viewtopic.php?f=13&t=6354 |
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| Author: | Sunny [ Sun Mar 03, 2013 11:46 am ] |
| Post subject: | Combi Meter RPM signal |
Hi folks, now the next bigger step will be to mount a haltech PS1000 to me 3S, but there is a problem with the rpm signal which comes oem from the ignition, but i will use a PWM output from the ECU to controll it, i'am pretty sure that many in here are using a stand alone ECU, there are two main questions i have and i'am glad for some help -how does the oem signal look like? - how get it converted in the combi meter? thanks greetz |
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| Author: | Nibbles [ Sun Mar 03, 2013 12:35 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
On the standard setup, the tacho is fed from the 'tacho' output from the igniter. I haven't put a sillyscope on to see what it looks like (I can if you wish) but I would hazzard a guess it will be a 5V or 12V pulse train, approx 2mS pulses, 1 pulse per ignition (2 pulses / revolution). I'm guessing you're fitting a haltech ECU and don't wish to use the standard igniter / coil, but do wish to use the standard RPM meter ? Are you going coil on plug or twin wasted spark ? |
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| Author: | two_OH_five [ Sun Mar 03, 2013 1:40 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
A very brief google suggests that you simply switch one of the haltech outputs to Tacho mode The first result is even about 3S-GTE http://lmgtfy.com/?q=haltech+rpm+output Mmmmmm, Haltech Tacos, arrgggggh |
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| Author: | Sunny [ Sun Mar 03, 2013 5:26 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
Hi, i will use COPs and yes standart rpm without igniter the output from the ingiter isn't a PWM signal unfortunetly so, it comes from the minus of the ignition coil over a zener-diod or something like this and gets converted in the combi meter for the rpm meter, there are a few guy here in austria which simulate this with a relais coil and a small electronic but this means a further part in the car which i want to safe, so my first plan is to get a better sight of things and then i will have a look to the combi meter electronic and the sinal and about i can get it working with the PWM signal from the ECU thats the master plan, plan b is the further electronic greetz |
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| Author: | Nibbles [ Sun Mar 03, 2013 8:14 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
I don't understand why you want to use PWM ? If the ECU has a 'tacho' output available which is a pulse train at 2 pulses / revolution then connect this direct to the tacho. No electronics needed. |
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| Author: | Sunny [ Sun Mar 03, 2013 9:58 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
Hi, the issue is the old toyota ignition / rpm signal signal which is not compatible with todays signals, even the main distributor of haltech here in austria knows that issue and told me of that, i think there is no specific tacho output looks like a brain storming to me  greetz |
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| Author: | Nibbles [ Sun Mar 03, 2013 10:11 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
The forum linked by Steve clearly states there is an 'AUX' output on the ECU to drive tacho pulses. ARe you saying this is not the case ? |
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| Author: | two_OH_five [ Sun Mar 03, 2013 10:37 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
Use output DPO1 - it has selectable drive levels http://www.haltech.com/wp-content/uploa ... Sports.pdf Outputs can be set to drive a tach http://www.haltech.com/wp-content/uploa ... ons_v2.pdf The only issue might be that it requires a high level signal like old skool gauges that were wired into ignition coils (unlikely) If that is the case then you need some trickery with inductors and a transistor/FET to generate the high level pulse As an aside it's unlikely that the stock uses PWM if it's driven of the igniter circuit. It's more likely to use frequency modulation However assuming the tacho is an inductive coil analog meter either system will probably work |
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| Author: | Sunny [ Sun Mar 03, 2013 10:46 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
Hi, 205 i think you has it, the old school system is the problem, but possible i can get it working after a look to the combi meter electronics and what he do with the igniter signal...if he do anything with it looks like my friend who did the ic pump controll unit for me has a further job greetz |
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| Author: | two_OH_five [ Sun Mar 03, 2013 11:13 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
Given the number of celicas running huge fast'n'furious tachos it seems unlikely that the rpm signal is hugely different to the norm |
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| Author: | Sunny [ Tue Apr 30, 2013 6:13 pm ] |
| Post subject: | Re: Combi Meter RPM signal |
Hi, here we go http://www.msextra.com/doc/ms2extra/MS2 ... m#tachoout looks like i found what i want greetz |
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