Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on

Re: Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on (Guest)

Sun, 05 Jul 2015 14:21:11 GMT

ESSDUB you have done it again. Set the needle as per when running, returns to zero and gives the right read out when running.

Solution - tacho needle jumps up to a higher rpm when key is turned to on, then start the car and set the tacho needle as per rpm (from digital device) and it will all be fixed.

Cleared ECU codes, been for two drives and engine light is not coming on. For today it seems to be good :)

Re: Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on (EssDub)

Sat, 04 Jul 2015 19:05:24 GMT

Is that instrument cluster the original one that was in the car? There are known 'issues' with the waferwire board behind the cluster being different from model to model. If someone has tried to change it and not used the original board, all kinds of funky things can happen lol.

The tachometer needle always will 'twitch' when power is applied, as its then looking for a signal from the coil to tell it how many revolutions the engine is doing. its nothing unusual :)

IIRC, there is a single-wire plug at the diagnostic port that can be used as a coil signal, to read engine RPM. You could try using that and take readings from there.

Re: Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on (Guest)

Sat, 04 Jul 2015 18:58:25 GMT

Thanks ESSDUB, something electrical is an issue, as the factory boost gauge needle also goes sky high.

Unsure where to find a guide to what the tacho/rpm signal should be or what setting on a multimeter to measure it, or how to diagnose the cluster (basics of diagnosing a working or faulty cluster).

Think its something else as the needle didnt jump up before when the keys turned to on. Does anyone notice there tacho/rpm needle jump even slightly (when keys turned to on).....

Re: Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on (EssDub)

Sat, 04 Jul 2015 18:43:29 GMT

The needle is not set up properly, so one would assume its been removed at some stage, maybe to fit some aftermarket dial faces. Remove the needle, turn the key to 'ON', put the needle back on at the 0 mark.

For the speed sensor issue, its tougher to diagnose, but you would want to check that the ECU is getting any kind of 'SPD' signal at all. I've got the wiring pinouts for that year somewhere, so i'll look at it later.

Re: Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on (Guest)

Sat, 04 Jul 2015 15:49:57 GMT

Sorry - its a 1993 mr2 sw20 3sgte .... exactly like this youtube video only higher ....

https://www.youtube.com/watch?v=2Sk1Bk7qPpw

thanks anyone who can help with ideas

Re: Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on (5SGTE)

Sat, 04 Jul 2015 15:45:36 GMT

What engine/year car?

Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on (Guest)

Sat, 04 Jul 2015 15:36:12 GMT

Any ideas why - the key at the on position, the rpm jumps up to 1500 (the car has not started), and the boost gauge (factory) lifts as high as it can. Start the car and the rpm responds to throttle but it sites 1500 rpm higher than what it should.

I have a AVCR and it is reading the correct rpm, however the tacho/rpm cluster shows 1500 rpm more.

If I go for a drive the engine light comes on, fault code saying no speed signal for more than 3 seconds above 3000 rpm. Speedo is working.

Anyone with guides or advice when it comes to electrics....

Cheers