Speedo Amplifier Issue

[white13]

I’ve replaced my speedo recently for a working unit but it seems to read just below the correct speed. I’ve checked the correct speed with a sat nav but the speedo reads around 5-15 mph below the actual speed depending how fast I’m going. Reads 30mph when I’m doing 25mph, and 80mph when I’m doing 70mph etc.

I’ve carried out the speedo amplifier checkas per the instructions in the picture below. It failed the test keeping battery voltage at all speeds. Does anyone know where the amplifier is? And what the issue may be if it’s reading battery voltage continuously?




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[white13]

Any ideas on this?


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[R3K1355]

Guessing it's a problem with an earth somewhere, corroded connection or similar?

Isn't there a little whatsit on the back of the instrument cluster to adjust the speedo slightly - to take into account changes when using different sized wheels??

[white13]

Not sure about the adjustment on the cluster but I’d be interested to know if there is.

Is the amplifier inside the speedo itself?


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[green_rs13]

there is no magic amplifier box. if it actually exists it will be built into the clocks. although ive had clocks to bits before and not noted anything special.

[polcastrol]

There is this: http://forums.nicoclub.com/s13-and-s...p-t618567.html

My lhd euro s13 had a potentiometer on the rear of the cluster, adjustment range was +-50km/h.

http://www.nissansilvia.com/forums/t...orrector-mkii/

[R3K1355]

The Potentiometer is what I was thinking about

[white13]

Don’t know why they’d give you a speedo amplifier test in the manual if it doesn’t exist.

I’ll check both speedos for the regulator on the back


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[ANDY black s13]

I was thinking the stuff in the diagram is for the diff oil cooler as that's triggered at over certain temp + speed
amplifier could be a miss translation as common with nissan/jap parts
my guess it will be out if the rolling diameter of wheels/tyres used is larger than stock
and the diff ratio if that's been changed
tweak the Potentiometer should sort it ,I think it's marked + and -

[Actual_Ben_Taylor]

If you look at PD-30 in the manual it shows you what differential oil cooler relay-1 connects to.

The speedometer amplifier appears to be part of the combination meter (looks like it's only there to trigger differential oil cooler relay-2 when the speed gets over 6mph).

[white13]

Yea I couldn’t find it anywhere in the wiring diagrams so thought it may be part of the speedo itself, or for a different model maybe


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[green_rs13]

if only the pot on the back of the clocks would double the readings. my speedo reads about half actual speed.

[ANDY black s13]

if only the pot on the back of the clocks would double the readings. my speedo reads about half actual speed.

you running a z32 or RB25 gearbox with stock speedo sensor?,recall people get that when doing the swap

[skyshack]

Speedo amp has nothing to do with the precision of the speedo reading.

A transistor has failed. It is part of the electronics on the speedo head and provides a switched ground output from the speedo to the diff oil cooler pump, via 2 relays. The oil cooler pump only runs when speed is greater than 6 mph and temperature switch on the diff is on. If it's not working the diff pump won't work but it's no great loss as no one has ever reported hearing the diff pump working (people that have removed them claim the pipe work and cooler has never seen oil). Nissan fitted a finned rear cover that holds 0.6L more oil and this cooler for Europe, one or the other would have sufficed.

All OEM speedos read about 10% high. Mine shows around 33 mph at 30 mph, 77 mph at 70 mph. Mazda 323 GXi also reads about the same.

Yours is a little bit faster. What tyres are you running? If they are smaller rad than stock you will have a fast speedo. You can probably go up one size on profile 40 > 45, 60 > 65.