Chattering relay in dash?

Lazz · #1 (**permalink**) 05-05-2008, 08:58 PM

have an odd problem here. it apperas that a relay/ electrical device behind the instument cluster is chattering away all of a sudden. it also seems to chatter faster under harder accelleration. no noticable performance loss. anyone have any ideas?

oz3litre · #2 (**permalink**) 05-05-2008, 09:32 PM

Where exactly does the noise appear to come from? The relays are in the fuse box under the dash. I had relays on my 1984 GTV rattling like mad and it turned out to be caused by the power wire on the thermo fan shorting against the radiator mounting. If your noise is coming from behind the dash it might be one of the air con stepper motors. There are three of them and the nylon gears wear and start to tick. I have one on the left hand side doing that. The fix is to replace the gears with brass ones. This is a bit of a bugger of a job and not one I have yet attempted. One day I will have to grit my teeth and get into it. Many people on the BB have done the job and can offer advice. Here are a couple of links to info that I have collected:

Alfa 164 Service Bulletins

alfapro.com - access methods

Good luck!

E.T. · #3 (**permalink**) 05-14-2008, 02:29 AM

Quote:

Originally Posted by Lazz

it apperas that a relay/ electrical device behind the instument cluster is chattering away all of a sudden.

Alfisto Steve · #4 (**permalink**) 05-14-2008, 09:02 AM

Quote:

Originally Posted by Lazz

have an odd problem here. it apperas that a relay/ electrical device behind the instument cluster is chattering away all of a sudden. it also seems to chatter faster under harder accelleration. no noticable performance loss. anyone have any ideas?

Lazz · #5 (**permalink**) 08-13-2008, 05:17 PM

ET the problem sounds similar to yours in that it hicupps at light acceleration . Steve its a US model '91 S. It's not in the fuse panel its sounds as if its directly behind the tach. It went away for a month or so and has just come back with a vengance. Any help would be appriciated. Thx

Alfisto Steve · #6 (**permalink**) 08-13-2008, 07:55 PM

Quote:

Originally Posted by Lazz

ET the problem sounds similar to yours in that it hicupps at light acceleration . Steve its a US model '91 S. It's not in the fuse panel its sounds as if its directly behind the tach. It went away for a month or so and has just come back with a vengance. Any help would be appriciated. Thx

E.T. · #7 (**permalink**) 08-14-2008, 02:59 AM

HI, the good news is that I finally got rid of the problem, for 99% !

to cut it short : it's the EVAP -fuel fumes recirculation valve. It is located in left fender well, you need to lie down and look for a two-wire Bosch connector plugged into a little solenoid valve which is attached to a little canister. For more convenient acces you can remove the left headlamp.

This worked for me, I haven't supplied this info to the forum since I have not fitted a new valve yet, so not 100% sure if it won't come back. Although, the old valve is broken for sure- it has 4 KILOohms of resistance and should have about 50 ohms, and obviously doesnt click when supplied with +12v.
So now I have it disconnected and the car runs great. I also disconnected the fumes line that comes from the back of the car to that canister to release pressure from tank, I know it polutes more but it's temporary until I fix it.

As I wrote in my post above, I had my car conected to a computer which showed no errors. Probably because the valve still had resistence, so ECU recognized it as beeing operative.ECU starts to operate the valve when the car warms up a bit and under conditions which let the fumes to be sucked and burnt, namely under acceleration -which is exactly when my car started to hiccup and click. Ecu supplies constant +12v and swithes ground momentarily a few times over several seconds to open the valve and let fumes into the intake manifold. I suppose while switching ground and facing huge resistance of the valve, the ECU went into some uncontrolled state and switched the ground between the A/C relay which I heard chatter at high rate. I have no idea how exactly that might hapen, but to me everything seems to correspond.Now it also looks reasonable that when i disconnected AFM or IAC the car wolud not try to operate EVAP due to switching into pre-programmed default fuel map ( limp home mode ).It was quite misleading.

At first I suspected the valve was shorted internally, which would even be more likely to cause strange behaviour of the ECU, but luckily it isn't. I learned that in some Hondas this valve beeing shorted would cause the ECU to fry...

I hope this solution will also work for you, though I think 91-93 US cars use different part number and different motronic ECU.
Please let us know, it seems to be an example of a very rare failure.
E.T.