The tach on my '94 stopped working all of a sudden. I have searched and searched but can't find any help fixing the issue. All of the other gauges are working fine. Can anyone tell me how I might go about troubleshooting this issue? I have no idea if it's the signal into the tach or the tach itself. Thanks.
Tachometer Stopped Working
- Thread starter Kmart
- Start date
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Is the key on?
Is the engine running?
Serious questions to get to the bottom of things.... starting at the beginning.
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- #3
Yes to both. The engine is running well, and all of the other gauges function normally. Tach was working fine and then just quit working. It is showing 0 rpm as if the engine isn’t running. Shifts and drives normally...just no tach indications.
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- #4
I don’t know where the signal for rpm comes from, and I don’t have a wiring diagram, so I am not really sure where to begin to look for an issue.
Calling @Malleus and @gummycarbs One of them will have the wiring diagrams and the info. I'm thinking it comes from the crank sensor, but it MAY be secondary and come from the ECU, OR the tach is shot and just need to replace it. (or even the distributor)
If the crank sensor wasn't working, it wouldn't be running at all.
As far as used replacement parts......
@arcteryx
@slow95z
If the crank sensor wasn't working, it wouldn't be running at all.
As far as used replacement parts......
@arcteryx
@slow95z
Could be the ignitor/coil going bad. I'm pretty sure that's where the tach is connected to. Before you replace it though, you might try unbolting it and cleaning the mounting points and bolts which are the grounding points as well. Could be corroded if you live in an area where they salt the roads.
Resolder circuit board and give that a shot. I’ve had this work on a Hilux.
After wheeling for a few days my Tach started acting up. It was most always when using cruise control and was exacerbated by driving over bumps. I haven't had a chance to open up the EWD yet to trace out the circuit. Hopefully you can save me the trouble of doing that.
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- #11
Thanks for the replies. I have definitely tried the smack method - no luck. I think I will have a look at the ignition coil first and then maybe pull out the cluster to check for broken solder joints. At least I could do the nifty temp gauge mod then too.
Landtank, I would love to help you with the EWD, but I don’t even know what that is
Landtank, I would love to help you with the EWD, but I don’t even know what that is
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- #12
EWD = Electical wiring diagram. Should have figured that out from the post...oh well.
the signal comes from the igniter circuit. I will go grab a color code off of my 93, my remote start is tapped into it and so is the new Tach feed for my swap. The black wire with silver bands is your signal wire. I'd like to add, that scoth lok wire tap and all the others on my vehicle were there when I bought it...I used the correct ones where available and lef the others as I have had bad experiences removing them in the past.
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- #14
@LandCruisinMy93 Thank you very much for the helpful pic and info! I will try to start my troubleshooting there this weekend. Do you happen to know how I would check the signal with a multimeter (of it’s possible to do so)? I guess I should see some sort of voltage with the engine running? Thanks!
The igniter puts out pulses that you're not going to be able to see with a DMM.
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- #16
Hello all - I haven’t had a chance to troubleshoot the tach further because I have some additional issues with the truck now, and I am wondering if they are related. Check engine light came on, and is showing codes 12, 26, and 71. Truck is idling very rough, acceleration is quite poor until higher rpm, and the transmission is shifting gears early unless I floor the accelerator.
I believe the codes are 12: Engine speed rpm sensor circuit; 26: Mixture control continuously rich; and 71: EGR system malfunction.
A couple of days ago I had the CEL with 12 and 71 with no real symptoms and the light cleared on its own. Now it’s back on with the symptoms and codes described above.
Any idea where to start? I could live without the tach when the truck was running fine, but I need to get this thing figured out given the terrible performance.
Thanks in advance everyone.
I believe the codes are 12: Engine speed rpm sensor circuit; 26: Mixture control continuously rich; and 71: EGR system malfunction.
A couple of days ago I had the CEL with 12 and 71 with no real symptoms and the light cleared on its own. Now it’s back on with the symptoms and codes described above.
Any idea where to start? I could live without the tach when the truck was running fine, but I need to get this thing figured out given the terrible performance.
Thanks in advance everyone.
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- #17
I am wondering if it’s the ignition coil causing the code 12 and loss of tachometer. Or would that be the ignition control module? It’s a daily driver, so hoping I can figure this thing out.
The igniter supplies the tachometer signal, not the ignition coil.
If the igniter or ignition coil was bad, the engine wouldn't run.
It seems to me that you're getting some unrelated codes. I would look for chafed or burnt wires that pass next to the EGR pipe or possibly through the firewall by the ECU.
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- #19
Thanks - I will have a look at this.
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- #20
Just wanted to post a follow up for anyone who has a similar problem. The ignition control module was bad, but apparently it was only the tach signal that was bad. A tune-up took care of the random codes I was getting, and the engine was running fine but the tachometer was still not working. I swapped the Ignition Control Module with a new one, and presto the tach started working again. Interestingly, the first aftermarket ICM I bought from Rock Auto (Intermotor brand) was faulty...the engine would not start. I bought another ICM from Autozone, and that one did the trick. Hope this helps someone along the way. Cheers.
