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Tachometer doesnt work, RPM function on S-AFC doesnt work

Ok, So the car was delivered today.

Couple of issuses I'm working on, that have me stumped. For startes, the tachometer doesnt work. With the car turned OFF, the needle is at the 9k position. With the car started, it stays in the 9k position. Also: the RPM function on the S-AFC doesnt work.

What could be the problem?


I didnt have much time to troubleshoot the issue, I had to get ready to come to work /ubbthreads/images/graemlins/frown.gif


tia,


Geoff
 

Polish

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Jan 10, 2005
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The RPM signal wire going into the AFC, I'd check that. Perhaps the splice came apart.
 

I thought about that too..... But the Tach doesnt work either..... /ubbthreads/images/graemlins/dunno.gif
 

Usually those 2 don't even use the same signal. /ubbthreads/images/graemlins/dunno.gif If I recall, the AFC instructions are to connect the AFC tach rpm wire to one of the CAS signals. The dash tach gets its signal from either a tach driver module on the coilpack (1990 DSM and older Mitsubishi) or from the "TAC" output of the transistor on newer cars.
If you mix components, say a 1991+ ECU on a 1990-style ignition system, the ECU will screw with the tach pulses. Is this something that just started?
 

Yes Jeff,

From what the previous owner tells me, it just stopped working.
The car is a 91 GVR4 with 91 GVR4 harness that came with the car.
I really dont know where to start as far as the tach is concerned, however I'll check to see what ECU is in the car, and the coil paxk. I would ASSUME the coil pack is a 91+ because it's connector is specitif to 91+ cars.....
 
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**Update** I tapped the the gauge cluster, and the needle fell back to it's starting position. My only question iws HOW THE F it got stuck at 9K!!!

Anyhow, I traced the S-AFC issue...... YUP!! Broken green wire. :b

BrokenSAFCwire.jpg
 
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GVR4ZUM

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Jul 8, 2002
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1,455
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SoCal, USA
I can't tell, was it soldered or just twisted on. If you have access to soldering iron, solder it and put electrical tape.
 
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