Hello guys, I had my Hicas-light that came on since a few weeks. It only came on when I drove my car on the highway for more than 5 minutes at speeds higher then 90 km/h. Fluid level had been topped up. No problems were found with conzult and neither in "self-test mode". The car didn't do this before. After a good thinking I tried to remember when it first happened and what was changed to the car then.

The last thing I changed was connecting the rear speakers. Normally, in the '90 model, there is a standard amplifier for the rear speakers in the back. The headunit amplifies the front speakers and a low-level signal is send to the back. Since the rear amplifier is gone in my car I thought, let's use the wires that go to the back to send the high-level signal to the rear speakers. Big mistake!

It took me a while to figure it out because monday I had to go somewhere and use my GPS. I decided to switch the radio off to hear the GPS and then the Hicas-light didn't came on. I thought it might have been a coinsidence and tried it on the way back. Again the Hicas-light didn't came on. I then disconnected everything from the radio and connected 1 thing at the time and went for a test everytime I connected something.

Since the rear speaker or not connected anymore, problem is solved. I don't say that this is the case everytime but consider it a probable cause in case you have a problem with the Hicas-ecu.

 

Mike

That is strange, struggling to see the connection between the rear speaker cables and the hicas, usually if hicas light comes on when on the highway / motorway is due to steering wheel input error, either the steering wheel angle sensor or if the wheel is way off centre.

 

Anyhow I am going to look at the circuit diagram now as I am interested as to how this could occur the way you say, will come back once I have traced it out see what I can find.

 

Jeff

Jeff, I did the test, believe me.

Every wire with a current sent trough creates a magnetic field. Since no wires are shielded in the car, the rear speaker wire could give some sort of interruption. Btw, more stories like mine on the internet.

 

Mike

Oh yes, and I've put an extra earth to the radio too.

Jeff, I did the test, believe me.

Every wire with a current sent trough creates a magnetic field. Since no wires are shielded in the car, the rear speaker wire could give some sort of interruption. Btw, more stories like mine on the internet.

 

Mike

 

Hi Mike, not saying your wrong just trying to work out the connection between the two, having just looked at the wiring diagram for both the HICAS and Speaker system nothing is shared, and whilst agree odd faults can be caused by inducted current, the speaker output from the head unit is a very low voltage signal and as such would not have enough power to cause such an issue.

 

They do share a power supply rail in the fuse board however, that is all I can find, again no amount of thinking can come up with a way this could be an issue. In fact using the speaker cables in the way you have is fine and commonly done, the European and UK spec zeds had the small powered signal booster fitted to increase the rear speakers performance, however the Jap import does not and so uses the cables in the way you have but from factory without any issues.

 

Just to make one point, there are in fact many shielded cables used on the zed and do work where sensors could be compromised by induction from close cables.

 

To be honest I do not see how this could happen, however your seeing it happen, car electrical systems can do some strange things but after 20 years on zeds this is a first for me.

 

Good luck with your investigations.

 

Jeff

Well, the problem is solved since rear speakers were disconnected, that's all I can say. Could have been a big bad dream :biggrin:

I have heard this before from a skyline owner with a boot sub install.

Every time the subs were going some, the rear felt twitchy and caused the rear steer to spaz out.

A rewire and relocation of some cabling and problem was gone.

It sounded strange to me but electrical interference can cause some very odd issues.

Well, the problem is solved since rear speakers were disconnected, that's all I can say

 

Where were the rear speakers disconnected?

Rear speakers disconnected on the dashbord-side.