I am getting a code 14 and intermittent loss of power steering. I understand code 14 is speed sensor, my speedometer is working fine even when the power steering fails, could they be related? First thing I will do is clean the connectors on the speed sensor, what else can I do to diagnose?

 

Thanks, Dan

Did you check the fluid level Danny?

Did you check the fluid level Danny?

 

I have done yes and it's fine. I have gone out in the car this evening and it's doing it again, if I switch the ignition off and back on again it's fine for a mile or so, also the fault code 14 has not showed tonight at all..

Check with consult that the ecu is always getting a speed signal. If it is, then it's an issue with the wiring to the hicas/power steering control unit. If the ecu also struggles to get a speed signal, it could be a faulty speedo or converter chip, since the speed signal goes from the speedo to the various control units. These cars have speed sensitive power steering, where the faster you go, the lower the assistance becomes. If it can't tell what speed you're doing, it'll drop into failsafe mode and apply next to no assistance. That's why it's fine at first, until it decides there's a problem and simply stops doing it.

I have plugged my laptop into it and gone for a little run out, I had several gauges on screen including water temp rpm and speed km/ph and km/ph just stays at zero..

 

Thanks

There's your problem then, now you have to find out why.

 

If your speedo has been converted with a chip, remove it and see if the speed signal returns. Then fit a UK spec speedo so this hopefully doesn't happen again, since converter chips are known to go faulty. If it turns out its the speedo itself at fault, replace it. Or if you're good enough with a soldering iron, look for any dry solder connections and apply fresh solder to them. Could also be a broken wire somewhere in the dash loom, but not as likely as a chip or speedo fault. It's not a faulty sensor, or wiring from it to the cluster, since your speedo is still showing you what speed you're travelling.

There's your problem then, now you have to find out why.

 

If your speedo has been converted with a chip, remove it and see if the speed signal returns. Then fit a UK spec speedo so this hopefully doesn't happen again, since converter chips are known to go faulty. If it turns out its the speedo itself at fault, replace it. Or if you're good enough with a soldering iron, look for any dry solder connections and apply fresh solder to them. Could also be a broken wire somewhere in the dash loom, but not as likely as a chip or speedo fault. It's not a faulty sensor, or wiring from it to the cluster, since your speedo is still showing you what speed you're travelling.

 

Thanks very much, no it's a UK car with UK clocks. When you say look for dry solder do you mean on the circuit board on the back of the clocks?

 

Cheers

If it's already a UK speedo then fair enough. And yeah the board on the back of the speedo. Not the printed sheet thing on the back of the cluster, but the actual board on the back of just that one gauge. You need to open up the cluster and remove the speedo to be able to get at it.

Thanks very much! I will get onto it tomorrow night.

No problem mate. The only other thing it could be I think is a loose connection or broken wire in the loom somewhere, and given that neither the hicas or engine control unit are seeing the speed, instead of just one, I'd assume the issue is before it splits and goes in two different directions. That's assuming it does actually split, and it's not passing through one to get to the other. I wouldn't know without looking at the wiring diagrams.

I have swapped my clocks over for an indiglo set I had lying around in the garage and went for a little drive, when I took them out they worked perfectly (6 months ago) now I am getting no speedometer at all with these gauges and as predicted still no speed reading from the ecu.

 

Is there any way to test the speedometer circuit boards once removed? Also, maybe I should now be actually testing the gearbox sender, should I be looking for a steady voltage?

 

Thanks, Dan

If both clocks both do the same thing, then it's not likely them at fault. It's not the gearbox sensor or wiring from it to the clocks, since the speedo works anyway. It'll be a broken wire from the cluster to the ecu and hicas.

Unless it passes through one unit to get to the other anyway. If that was the case then it could also be a fault with the first of the control units. Like I say, I've not looked at any wiring diagrams to find out, since I don't have any.

Ok, thanks.

 

I don't know if this would make a difference but over the winter I replaced my hicas rack with a lockout bar and have had the hicas light on ever since and for the last 2000 miles or so it has been fine. The problem has only come apparent since swapping my ecu from a mines to a nistune, but I swapped it straight back to confirm it was the ecu but the fault is still there ...

 

thanks

The hicas light being on once the rack has been removed is normal of course, but the control unit still controls the speed sensitive power steering. Maybe you've disturbed the wiring in the passenger footwell when changing the ecu? Trace the speed signal wire back from the ecu and hicas control unit, and see if you can find a break in the area.

Will get on that tomorrow and do a continuity test on pin 53 form the ecu to the back of the clocks and check for any damage to the sheath. I cant find a pin out diagram for the Hicas control unit though to show me which is the speed sensor pin and to where it goes to?? Will it be the same colour?

 

Thanks,

I'm not sure, but there is a z32 hicas manual knocking about online somewhere in pdf format, so I'll have a look and post the link once I find it.

Here you go, not sure what page it'll be on, but it seems to include wiring diagrams:

 

http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=st&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=29&design=default&total=98

 

Fingers crossed it covers both hydraulic and electronic versions of the hicas. What version do you have by the way?

Page 67 fella. :)

Cheers, not a clue, how would I tell?

Unless I've read the diagram wrong on that page, it appears to be pin 6, in the larger wiring plug. It shows the layout of the plug in the middle of the diagram.

Cheers,

 

When I get home I will measuring resistance between pin 53 at the back of the ecu and the other end at the back of the clocks, if there is resistance then I guess the only place left to test is the signal out on the back of the clocks, how can I test this?

 

Thanks

You'd need an oscilloscope to do that I think, to monitor the pulses. But if you've tried a different cluster already, then it shouldn't have an issue there. One hell of a coincidence if that is the issue!

I have just checked for resistance and it's there, also the cable at both ends have no kinks or damage. Where do I go from here?

 

As I understand it there is a signal coming from the gearbox as the speedometer works and there's resistance from the clocks to the ecu so the fault must be at the clocks??

 

Is there anything else I can check or test? Many thanks

If there's no continuity, then you will see resistance. It's continuity you need to be checking for, so you want NO resistance. ;)

Huh?, my ohms tester beeps when I test both ends of pin 53...