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Old 08-12-2012, 10:18 PM   #1
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Default MS1 installed tach not working, already tried resistor trick

Ok, been asking about this in my other thread linked below but thought I would break it out because it's a much more direct question than the previous lot and I have tried all the typically suggested solutions.

https://www.miataturbo.net/megasquir...45-w-ms-67313/

I installed a Brain built MS1 w/ Toyota COP and am not getting a tach signal. I have already tried bridging a 1k resistor from IG- to B+ in the diagnostic port, nothing changed. Also hard wired from the Yellow/Blue wire going into the ignitor to the cluster Yellow/Blue wire with and without the resister, nothing changed.

Is there something I am missing?

Can I go the route of running a tach signal from the MS? How do I check if I do/don't have a tach output circuit?

Can I intercept the tach signal going to the MS from the CAS to feed the gauge cluster?

Thanks for the help.
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Old 08-14-2012, 02:57 AM   #2
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Anybody have any ideas? Is there a procedure for troubleshooting this? I checked all fuses and they look good. Maybe a relay?
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Old 08-20-2012, 11:14 AM   #3
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bump this up. still looking for help.
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Old 08-20-2012, 11:37 AM   #4
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I half fried my ignitor once. the car ran but there was no tach output. do you have a spare ignitor to test?
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Old 08-20-2012, 11:43 AM   #5
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do you have a DMM?

test continuity between GND and IG-. if there's no resistance, pull off each coil until it goes away.

It's possible you have one bad output on a coil.


or better yet, check to see if your coils only have 3 pins, not 4.
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Old 08-20-2012, 03:11 PM   #6
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Quote:
Originally Posted by Braineack View Post
do you have a DMM?

test continuity between GND and IG-. if there's no resistance, pull off each coil until it goes away.

It's possible you have one bad output on a coil.


or better yet, check to see if your coils only have 3 pins, not 4.
Have tested with multimeter but will try pulling coils off method. Coils are 4 pin Toyota COP's.

If there is a band output on a coil, would it still spark correctly? Car is running great.
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Old 08-20-2012, 04:03 PM   #7
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I've killed a tach out on one of my coils, It was grounding the output signal, when I pulled the coil the tach came back albeit about 25% too low
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Old 08-20-2012, 04:47 PM   #8
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And by pulling you just mean unplugging the connector to the individual COP right?
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Old 08-20-2012, 05:20 PM   #9
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correct.
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Old 08-24-2012, 11:18 AM   #10
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Finally had a chance to test things last night, tested each coil output to ground on the DMM and no chime. Also tested the tach signal wire coming into the gauge cluster and got no voltage from that wire to ground with the ignition on.

I bought this COP setup off of another board member, any chance there is an issue in the ignitor? Ideas on the next troubleshooting step? Thanks.
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Old 08-24-2012, 11:20 AM   #11
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Not exactly how I said to test, but okay. I want you to test IG- to gnd in the diagnositics box in diode test mode. It should not chime.

no, the ignitor has nothing to do with the problem...you don't even have "an" ignitor, you have 4.
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Old 08-24-2012, 12:43 PM   #12
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We also tested with the DMM connected from IG- to ground in the diagnostic port to test resistance like you said. We had a hard time getting consistent results, probably due to not have a very clean ground or a very good DMM.

Results from that test were when all the connectors were plugged in, we got a dummy reading. No specific numbers, just a 1 to the far left of the digital readout (sorry I'm an electrical idiot). As we unplugged each connector 1 at a time, nothing changed. When I disconnected all the connectors, we started reading about 1.5 on the 20k Ohms setting of resistance. No one coil acted differently from the others.
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Old 08-24-2012, 12:46 PM   #13
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okay then. unsure the problem then.
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Old 08-24-2012, 01:04 PM   #14
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My understanding of the components goes like this...

Coil - wiring - Ignitor w/ connector - wiring - diagnostic port - wiring - cluster

Up to this point, (and correct me if I am wrong) I have ruled out the coils, diagnostic port and wiring. Are there any relays/fuses/switches/etc in the chain that could be blown and killing the signal. I have tested all fuses in driver foot well and they are good.

Maybe the cluster is bad? My speedo and fuel gauge work but the tach and water temp doesn't. So all the mechanical gauges work and all the digital/electronic don't. Although the warning lights and etc work.

In testing we also ran the tach output wire from the OEM harness side of the connector directly to the tach signal input in the gauge cluster connector and got nothing. This is one of the main reasons I'm thinking there is something wrong in the ignitor/ignitor casing specifically. What if the wiring isn't connected properly inside for just the tach output signal wire?? Possible?
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Old 08-24-2012, 01:12 PM   #15
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the ignitor is gutted. it's just a connector now.

check your meter fuse.
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Old 08-24-2012, 01:16 PM   #16
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Quote:
Originally Posted by Braineack View Post
the ignitor is gutted. it's just a connector now.

check your meter fuse.
Checked the meter fuse previously and it was fine.

Any info in this thread sound like it might apply to me? I got lost in the troubleshooting that Reverant was doing.

https://www.miataturbo.net/ecus-tuni...ng-cops-54936/
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Old 08-24-2012, 01:21 PM   #17
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I've blown that fuse numerous times from those wires on the trans..at least 3 times. always because the trans in question had bad connections and the bare wire touched the housing and blow the meter fuse instantly.
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Old 08-24-2012, 02:29 PM   #18
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Ok, I will take a look at it again when I have a chance.

Is there an easy way to check if my MS has a tach output circuit built into it already?

Also, going to try and test putting the original coil system back on the car to see if the tach reading comes back. They way I will know if it's the COP setup I bought.
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Old 08-24-2012, 02:30 PM   #19
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if it was built for a 90-95 then i doubt i did.
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