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wrong tach voltage?


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kakarotsaiyan 
Member - Posts: 11
Member spacespace
Joined: January 05, 2010
Location: Alberta, Canada
Posted: November 08, 2012 at 8:18 PM / IP Logged  

Hi,

Ive just installed a Remote start on a manual transmission 2006 Ford Focus ST 2.3. remote start is the CT-3271 Pro Start.

I am having problems getting the thing to work or should i say i cant get it to go into ready mode ive tested all wires and they all seem fine apart from my tach wire.

I read that it should provide between 1-6 volts ac when running but but when i test mine its reading at 30 Volts AC? i currently have it hooked up to an injector wire.

I have also tested both wires to the injector and i have tested both wires going to one of the spark plug ignition coils but everything reads the same 30 VAC ?? is there a  better place to connect the tach wire too?

Im assuming that the high voltage reading is stopping the remote start from recognising it as running?

Any help would be super appreciated

Thanks

auto enhancers 
Copper - Posts: 203
Copper spacespace
Joined: April 09, 2012
Location: Indiana, United States
Posted: November 08, 2012 at 10:14 PM / IP Logged  
It should be the non common wire at the injectors.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: November 09, 2012 at 12:45 AM / IP Logged  
And erratic DMM voltage readings are to be expected.
Those are not only on-off signals of ~0V & ~12V, but also subject to spikes when the circuit is opened - eg, IgCoil spikes of 200V.
howie ll 
Pot Metal - Posts: 16,466
Pot Metal spacespace
Joined: January 09, 2007
Location: United Kingdom
Posted: November 09, 2012 at 3:26 AM / IP Logged  
If this is a Duratec or Zetec engine it probably shares the same injection system as its European cousins, always gone to a non-common injector wire with no problems.
Look at something else such as the Prostart's NSS wire. Is that grounded via the parking brake?
howie ll 
Pot Metal - Posts: 16,466
Pot Metal spacespace
Joined: January 09, 2007
Location: United Kingdom
Posted: November 09, 2012 at 3:27 AM / IP Logged  
You have to sometimes ignore readings and use common sense.
If I don't get the "assumed" reading via DMM, I have LED testers and I know what to expect.
kakarotsaiyan 
Member - Posts: 11
Member spacespace
Joined: January 05, 2010
Location: Alberta, Canada
Posted: November 09, 2012 at 10:14 PM / IP Logged  

Thanks for the replies,

How do you mean the non common wire? because i checked every wire on all 4 injectors and each wire is a different color each injector has a purple with a different coloured stripe and a green with a different coloured stripe. i did however test both of the 2 wires going to the injector and got the same reading.

i tested the the parking brake wire and it gave a 12 volt reading i will have to confirm that it goes to ground when applied... more testing tomorrow i think.

but if you could shed a little light on the " non common" injector wire where all the wires are a different color that would be great.

Thanks again.

howie ll 
Pot Metal - Posts: 16,466
Pot Metal spacespace
Joined: January 09, 2007
Location: United Kingdom
Posted: November 10, 2012 at 2:07 AM / IP Logged  
No not really, I've a feeling you're doing something wrong.
Injector engine run, 1 wires = 12.6 VDC.
Other wire = about 1-5 VAC.
As for the parking brake they are ALL wired to switch to ground so naturally with the brake released you are getting 12v+ from the warning light.
You are making the normal beginner mistake. Two much use of testing tools, too much analysis and not enough common sense, relax and when I say test if it works, i.e. temporarily attach your tach wire and test via the R/S.
howie ll 
Pot Metal - Posts: 16,466
Pot Metal spacespace
Joined: January 09, 2007
Location: United Kingdom
Posted: November 10, 2012 at 2:15 AM / IP Logged  
Get your hands on the pin-outs of the engine management, look for ignition coil, 10 VAC. M1 or M3.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: November 10, 2012 at 4:33 AM / IP Logged  
Howard is all too right with his "too much use of testing tools.
Most fail to realise that both ends of a load - eg, bulb, relay or injector or ignition coil, resistor etc - are the same at both ends if no current flows.
Hence the switched sides of handbrakes & injectors read +12V when not "on".    
Normally the +ve side of an injector is connected through its own resistor aka ballast which in turn is connected to IGN +12V. The other end (-ve) is then connected to ground/earth by the ECU to fire/open the injector. It is equivalent to (the primary side of) an ignition coil whether a points or electronic system (CDI and a few others excluded).
But measure either end of the injector (or IgCoil) with IGN on and the voltage will be +12V if it is not turned on - ie, points are open or ECU has not turned on the load).
And that 12V is despite the +ve end of an injector being 2-4V or 8-10V (depending on type) during normal "on" periods.
The above may makes sense one day, but until Ohm's Law (zero current = zero voltage drop) and "high-impedance" sensing (eg, voltmeters) concepts and their implications are understood, it's often pertinent to take heed of what people like Howard advise. (He is Platinum, AFAIK there is no technical reason why he is merely gold.)   
howie ll 
Pot Metal - Posts: 16,466
Pot Metal spacespace
Joined: January 09, 2007
Location: United Kingdom
Posted: November 10, 2012 at 5:36 AM / IP Logged  
The point is too many DIYers will either assume without testing = FAIL.
Not the case here but looking for exactly what is supposed to happen without knowledge of what the circuit is doing/supposed to be doing.*
Frankly I've had two new (to me) vehicles in the last month a Range Rover and a Mits L200 diesel truck where both failed to give me readings in the expected places. I simply moved the tach lead around to different suspected places till I found one that worked.
Or first poster should have tried one injector lead then the other till it worked or gone to a coil pack.
Or a camshaft position sensor.
Or pin 9 on the diagnostic socket (not all vehicles).
Or the engine management.
Or rear of instrument panel not the latest vehicles where the gauge pack is a processor and is only receiving data from the engine management.
* That comment is deliberately targeted at the myriad UNNECESSARY relay and diode questions on this forum.

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