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Discussion Starter #1 (Edited)
I just bought a super clean '96 4-runner for the wife to chase groceries and what not in.

It's a Two wheel drive with the 3.4 V6.

Every thing about this truck is like new, and it drives really great.

It only has one thing that needs fixing.

The tachometer.

When the motor is at idle, it indicates 1k. This seems normal.

At 70 MPH, the tach shows about 3k. I don't know if that's normal or not.

If you push the gas pedal to the floor, the tranny will down shift as expected and the truck accelerates like it should.

Here's the wierd part. When you make it run like this, the tachometer goes all the way off the scale. it goes down to what would be at least nine thousand RPMs if there were numbers down by the idiot lights!

Now, I'm pretty sure that the motor is not over-revving. I don't hear the stuttering sound of a rev limiter, and it doesn't sound like it's spinning too fast at all.

And I'm also pretty sure that 9k would scatter that baby all over the place.

The problem is the tach. It's a liar!

So...

Here's the question.

Have any of you guys seen this before?

Does anybody have any suggestions before I tear into this mother?

Thanks in advance for any help!

Fast Frank
 

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Stinks like fish
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Sounds like the instrument and not the motor. Maybe someone can come up with a diagram to show you how to trace down the wireing to the sending unit. It is probably that that is bad. If that checks out OK I am surprised that motor is still in one piece ;)
 

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Do you know if the Dash has been dissasembled for any reason, i.e. gauges taken out? 1K at idle is a little high, I'm wondering if anyone ever took the gauge needles off and didnt put them back on in the right spot.
You might try hooking a temporary shop tach up to it and checking the readings.

Tim
 

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Discussion Starter #4
Man, I don't have a clue if it's been apart or not.

I've owned it for about a week now.

The dash looks perfect, so I'm assuming that anybody that might have pulled it out knew what they were doing.

I was hoping that somebody would tell me what's driving the tach.

Is it reading the ignition, or does the computer send a signal to the tach?

I'm going to score a book for this thing, but the usual Haynes or Clymer won't tell me jack about how the tach works. The best I could hope for in one of those is a short paragraph that says "Pull these screws and take the tach out". Gee thanks!

Has anybody seen the Toyota service manual?

I'm wondering if it has decent wiring diagrams or not. If it does, I might pay whatever it cost. Otherwise, the cheapo clymer will have to do.

Thanks.

Fast Frank
 

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always a Toyota lover at heart
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just find a shop you trust and ask them to verify the RPM range, maybe its just a bad gauge or the needle was improperly set.
Sweet 4runner!
 

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krazy speedo?!?

check ur speed sensor. If u have one. Should be any electrcial connection on the body of the tranny. My Acura was doing the samething before I got rid of it and the VSS was out, quite common on Hondas.

hope it helps!
 

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Don't know about on the newer ones, but I had a friend that put a SR5 cluster in his non SR5 truck. The cluster was from a v-6 and his truck was a 4cyl. He had to adjust the tach because it was reading low because of less fires per rev on the 4cyl. There was a switch on the back or something to change it for a 4cyl. Maybe someone messed with it.
 

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If that motor was revin at 9k ud know cause ud hear it.
 

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9k, like a dude, I would hope you have enough car knowledge to hear 9k coming from a motor, if not you shouldn't be allowed to drive. 9k. hehehe my 3.4 is screamin at 5500 rpm, 9k would be a wicked cool exsplosion.

(ps check the ground wire for the tach. it has to be a grounded mint or it will read improperly.)
 

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Alot of the Toyota clusters have a little dip switch either on the back of the cluster or near the tach to switch from 4cyl to 6cyl readings. Make sure the switch is on 6cylinder.

Speed sensor will cause the tach to be out of whack....just the speedo or fuel managment.
 

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fast frank said:
Man, I don't have a clue if it's been apart or not.

I've owned it for about a week now.

The dash looks perfect, so I'm assuming that anybody that might have pulled it out knew what they were doing.

I was hoping that somebody would tell me what's driving the tach.

Is it reading the ignition, or does the computer send a signal to the tach?

I'm going to score a book for this thing, but the usual Haynes or Clymer won't tell me jack about how the tach works. The best I could hope for in one of those is a short paragraph that says "Pull these screws and take the tach out". Gee thanks!

Has anybody seen the Toyota service manual?

I'm wondering if it has decent wiring diagrams or not. If it does, I might pay whatever it cost. Otherwise, the cheapo clymer will have to do.

Thanks.

Fast Frank
The ECM gets the info from the ignition, then sends a signal out to the tach. I'd check the wiring harness on the instrument cluster and grounds like doc said.
 

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ShowStop said:
The ECM gets the info from the ignition, then sends a signal out to the tach. I'd check the wiring harness on the instrument cluster and grounds like doc said.
Actually, according the wiring diagram ( and just like most Toyotas), the tach feed comes directly from the ignitor.
 

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truck ~n~ tow
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Chas said:
I rev to 9 all the time
in my 4ag powered corolla
I rev to 12,000 all the time on my CBR... but wtf's that got to do with Trucks? I'll give it to ya it's at least a Yota!! This ain't no freakin' Corolla forum....LOL
 
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