I have a 88 TII chassis with a 86 S4 N/A motor all wiring is from the N/A car. After doing my swap and getting the car to run. I am unable to get the tach to function.

I am able to read HZ from the Trailing coil connector F-35 Y/L at that connection, I am able to read HZ at ME-02 Pin 10.

I have tried another cluster and that did not seem to work.

Any ideas?

 

Same issue man, S5 TII though. I just bought a ricey autometer 5 inch tach and mounted it in the glove box.

 

We are able to put a multimeter set to HZ on the back of the gauge cluster and we are able to read rpm through the meter. Is there a way I can find out if it is getting to my ECU?

 

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I believe pin 1X is one and the same as the signal going to the tach.

The trail coil has to actually fire both coils for there to be a tach signal.

Is there any other item in the instrument cluster that isn't working? As in a clue.

I've proven that if one runs a wire from the LEAD coils bullet connector to the TRAIL bullet connector, the tach will work normal. More or less proves if the trail coil or the tach itself is kaput/not working right. I'm a light weight and removed the two white connectors on the trail coil when doing this.

Is the gnd for the tach any good? Gnd #9 in the online diagrams.

 

My trailing is firing and still no tach, so it has to be either a flaw in the wiring or at the ecu...if you happen to figure it out let me know please.

 

I have included a jpg that you used in the past to help a fellow RX7 owner. I do not have a bullet connector on the trailing coil or off of the wiring harrnes. My leading and trailing coils are working, I did try pulling the plug wire out of the trailing coil and I had plenty of spark. As for the number 9 ground. I am very sure that ground is clean and secure.

 

The rest of my gauges work within the cluster, are you refering to pin 1 in the connector ME-01 Ground (B) Pin 1 or ME-02 Shift Indicator (B/W) Pin 1, On the ME-02 connector Pin 2 is the ground. Like I said I know my ground (9) is good because the rest of my gauges work. When you are refering to jumping the bullet connectors; Should I disconnect the F-35 connector and jump it to the Y/L wire?

 

WTF is that huge rod coming out of your console?

 

I was suggesting removing both F-34 and F-35. Then getting a piece of electrical wire and bare it at each end. Stuff one end in the black bullet connector on the LEAD coil assy and stuff the other end in the black bullet connector on the TRAIL coil assy. Then start the car and look at the tach.

I've done this in the past out of curiosity and find the tach will work just fine. It's just a *tool* to figure out which item is bad.....the trail coil assy or the tach itself. I suppose if you've idled the car and pulled one trail sparkplug wire off at a time and observed spark, then that would confirm the trail coil assy is working.

I see you already confirmed the gnd nine is good.

Does your coolant level buzzer work? It's something sort of in common with the tach. Sorta.

 

We did try pulling the plugs off each coil and we had plenty of spark, The coolant level buzzer has gone off a few times. That bullet connector you are refering to by the trailing coils is called F-39 correct? That is the only thing I have not had success at yet. Lets say we do the jumper trick and the tach still does not work. What could it be?

Like I said earlier we do get a reading on the dmm set to HZ. After looking at the wiring schematics the tach singnal goes to the tach, a buzzer, a speedsensor which is used for cruise control and 4AT which they dident have on the 86 S4 wiring.

 

Hydraulic e-brake

 

Also I've jumped the trailing from the leading coil via bullet connectors and it didn't do anything sooo is there any answer for that contingency??

 

If you pull F-35 plug off the trail coil, and can ring out (ohm out) the Y/L wire from there to the round plug on the instrument cluster, then the tach must be bad. Hard to believe you had two bad tachs though.

IF the car is idling at a normal 750rpm, what is the hz read at the tach wire at the round plug on the instrument cluster? The voltage?

Since you did the jumper b/t the lead and trail bullet connectors, I'd say it has to be a tach problem imho....if the wire has continuity b/t the F-35 and the round plug on the instrument cluster.