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plague of the bouncy speedo HELP!!


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Are the other gauges functioning normally?

Does your vehicle shift ok, no jolts or hesitation?

Is the bounce of the needle consistant or varies wildly?

Does the bounce occur if you manually put the transmission in 1st, 2nd, 3rd, Drive, Reverse?

Does the CEL come on?

Describe what happens when you take your foot off the pedal, does the needle fall back to zero?

 

Possibilities:

Intermittant break in the cable or connector to sensors or gauges

An issue with the ECU/TCU with regards to the signal coming from the VSS sensors.

Problem with the mechcanical "tab" drive mating the tranning to VSS-2

 

Long shot - try discconnect battery to reset ECU

 

Other than that I don't know what to tell you to try.

 

 

Anyone else....?

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as long as my foot is on the accelarater

it will hold at the speed im going(i think)

as soon as i let off, it will drop to zero

now on occasion it will hold, but not often

so when i am in traffic it starts bouncing

becouse im off and on the pedal

seems to work the same in any gear

trans seems to shift good, motor is running tops

scanner is saying the fuel, exhuast, ign, all operating good

all seems good except the speedo

and the a/c but god only knows whats wrong with that

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It still has a NSS

 

 

nipper

 

 

That function is built into the gear selector indicator. Actually a Park/Nuetral safety switch. The ECU just uses the signal for the P and N lights.

 

I don't think it's failing would cause an idle issue on an automatic.

 

I would think it's a a problem with the IAC

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That function is built into the gear selector indicator. Actually a Park/Nuetral safety switch. It just uses the signal for the P and N lights.

 

I don't think it's failing would cause an idle issue on an automatic.

 

I would think it's a a problem with the IAC

 

search 1507, its not the iac

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Tht switch is P R N D 3 2 1. It has many uses. Its not a just a start interlock switch. It also tells the TCU and ECU what gear the car is in. It just doesnt turn lights on and off.

 

 

Actually that is all it does, is complete contact for each position. Now some of the positions(P/N) are wired in to the ECU and Cruise, etc..., but just as signal.

 

The ECU sees voltage at a certain pins(when the light for that gear is illuminated) and interpruts it. The switch itself is nothing but simple sets of contacts. Splitting hairs I guess.

 

I just wanted to point out that this part doesn't have *logic* or any computing function. One could test if a poor connection in the switch was culprit by simply using jumper wires to simulate the switch being closed for a given circuit (P, N, D, etc...)

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search 1507, its not the iac

 

It is:

 

IDLE CONTROL SYSTEM MALFUNCTION (FAIL SAFE)

 

What do you think control the idle?

 

The Idle Air Control Vavle (IAC)!!!

 

It is not the only possibility, but a good place to start. Perhaps it has a loose hose? Loose connection?

 

 

You can't just dismiss it without checking it.

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