No speedo - Fixed!!!!

Northerner

Club Member
2D934AB9-508B-4C69-AD25-AB72C7CEE388.jpeg 1F3EBEEA-164A-4890-A649-0330C27C84BF.jpeg I may have a fix for the z31 speedo issue. Mine went dead ages ago so I’ve done the usual testing of the sensor in the gearbox as mine is a facelift which was fine. Even swooped over spare speedo I have which didn’t work. I’ve traced the wires to the speedo head which were all ok.
I’ve been searching the web for ages and found a thread from a Japanese owner and spent ages using google translator.
It seems there maybe an issue with the semi conductor which corrodes. Well I opened up my spare speedo after testing it to find the same corroded part. In fact it was green and it was loose. It even snapped off with light pressure.
Anyways I opened up the one on my car to find exactly the same.
I’ve ordered a few so watch this space.....
 

Northerner

Club Member
Got my new resistor today and it was a little tricky to remove and solder in again but got it done. Went for a drive and hey presto fixed!
For some reason Nissan uses a 9v resistor to obviously drop it from 12v to feed the speedo.
Unfortunately it means taking out the clocks and totally disassembling the clocks inc taking off the needles but it’s well worth it when done.

As you can see I used a bolt pressed against the side of the next resistor to help flexing or vibration. The cost was £2 and some patience
 

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Northerner

Club Member
Another update! After driving around I have noticed that the speedo is now 10mph out.
However I noticed an adjustable resistor on the speedo board which was set at 4 dots from the right. So thinking this must be the adjuster I moved it to 2 dots from the left. This made the speedo even more out so I changed it back till 2 dots from the right and using my gps speedo app found it to be 1-2 mph out. Result.
It meant that I’ve had the clocks in and out several times but it was worth it. See the attached picture to show the resistor.
 

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mrM

Club Member
good info ,i hope i never have issues with mine but this is good to remember as a lot of parts are hard to find/expensive these days for our z31s,cheap fixes are cool with me! EXTRA;)
 

scb1957

Club Member
Hi Northener, My speedo died about 4 years ago and been using GPS speedo, but when I get mine running again, I'll have a go at pulling the speedo out. I have had it out once before and it's a bit of a ballache. Need this power transistor to get mine running, before I can tackle the speedo.
 

Northerner

Club Member
They are about £2 on flebay. Just make sure sure do a decent solder joint or if not competent take it to a tv repairs! Good luck
 

scb1957

Club Member
Hi finally got round to sorting the Z31 out. Now have working headlamps and motors and have taken the speedo out to discover the exact same fault highlighted by you. Parts on order from E-bay, as per your photograph. Thanks for your input and info. Cheers Steve.
 

Ray MC

Club Member
Thank god for Northerner and his writeup because this happened to me too and I fixed it thanks to that legend. I feel compelled to add my experiences in hope that it may aid someone else in this timeless issue.

After weeks of soul destroying fault chasing, I narrowed the search to the 9v regulator just as Northerner described (although I was sent on many wild goose chases such as checking for a speedo cable, checking the pinion etc...). My symptoms were that the speedo needle would drop to zero then bounce back to the current speed. After a few more days, it stayed dead at zero. My 9v regulator had corroded too and it was blatantly obvious what the culprit was (spot the corrosion on the underside of the circuit board in the pic attached) . I ordered the exact part from ebay as listed by Northener and after it arrived (2 weeks later) I uninstalled the old regulator and installed the new one as I'm handy with a soldering iron. I'd recommend asking for help from someone who has basic skills, it's not too difficult.

I did not need to change the tuning screw as the speedometer read correctly by default after the install unlike Northerner. A specialist was going to charge me £250 minimum for looking at the cluster and a garage was going to probably fully tear down my car to identify the issue at a cost of who knows. This fix cost me 99p but the regulators came in a pack of two so... £1.98 in total. Happy days!
 

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Kieran Burke

Club Member
Got my new resistor today and it was a little tricky to remove and solder in again but got it done. Went for a drive and hey presto fixed!
For some reason Nissan uses a 9v resistor to obviously drop it from 12v to feed the speedo.
Unfortunately it means taking out the clocks and totally disassembling the clocks inc taking off the needles but it’s well worth it when done.

As you can see I used a bolt pressed against the side of the next resistor to help flexing or vibration. The cost was £2 and some patience
Hi, I have a problem with my Digital Speedo only working intermittently. I am looking at your photos of Speedo Head and can't figure out which Resistor you replaced. What colour is it? What is the bolt and nut doing. Very helpful, I think it might fix my problem also. Thank you very much. Kieran
 

Northerner

Club Member
I replaced the one to the left of that one! I think the bolt is to make sure that one does not flex or move. You can see the one to the left is green and corroded at the bottom. Not sure what the insides of your Speedo look like but I’d imaging it will have a power source so use a multimeter to check power in and out. Have you checked your Speedo sensor in the gearbox also?
 
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