Fan Fail light on for no reason!!!!

[DMC3165]

About a year or two ago I installed Dave M's Fan fail relay. For the first few months everything was good then I started getting an occasional flicker of the fan fail light usually after I'd driven in the rain. It would flicker on and off for a bit then go away. So I reprogrammed it to only come on if a fan went out and everything was good again.

Fast forward to this summer when I started using the A/C the light started to flicker again. So I tried reprogramming it again but this time it still flickers with both fans running. But it's no big deal just an annoyance so I left it alone.

However tonight for the first time the light came on WITHOUT the fans running! I put the A/C on then clicked it off and the light went out again. Any ideas what this could be about? Maybe a lingering short in my fuse box or something? I'm almost tempted to go back to the Y jumper so I'd never see the light again.

Damn Lucas electronics!:banghead:

[Spittybug]

I'm having similar issues. I think it may have something to do with the voltage comparison feature. I've started getting all kinds of flickering yet the fans are running fine. I'm going to reprogram them to just ignore the voltage difference once I dig out Dave' instructions (like you said you did). I have Toby's new fans, all the wiring connections have been cleaned and I have no other electrical issues of any type with car. This just seems to have gotten progressively worse of late. It also seems to be after the car has been running a while, not right away. Dave has always been very supportive of his products and hopefully we can feed back enough information for him to help figure out what may be going on.

[Bitsyncmaster]

It's hard to find those problems if I can't get the same failure. After DCS, I will look into it. It's most likely bad connections since your dealing with high currents. These units have not had any changes since day one. Maybe I need to do some averaging current checking in software but my current sensors have a good hardware filter on them.

If your having these problems, please list what fans you have, if you installed the circuit breaker bypass wire, and your battery voltage with the engine running.

You can always pull the light until you get the problem fixed but turning it off in software should stop it unless you really have a problem.

[WelmoedJ]

I also do have Bitsyncmaster's new Fan Fail and Fan relays.
I have put them in after swapping a defective original fan for another original (no history on it being good or not, but it worked).
I have also replaced the belonging circuit breaker with a wire (from the FF kit Dave supplies) between both relay sockets.

I did notice irregular behavior of the Fan Fail light shortly after A/C turns the fans on.
I blamed one of the fans as I could not determine which one caused the irregular flashing of the FF light.
As far as I recall it only happens when the A/C is on (and thus running the fans).
I haven't seen the light when the fans come on and while on to lower coolant temperature.

I'm now in the process of (long time planned) replacing the original fans with new low current fans from DMC EU.
Once that's done, I'll keep an eye on what's happening with the FF light.
I'll report back in a week or two.

[DMC5180]

No issues with the Fan fail light that I'm aware of. I have OE fans with Breaker Bypass wire. Then Again, I have not been paying that much attention to it. I forgot you could reprogamme it. I never changed it from how I recieved it. I guess I should look at the instructions again. It's been a couple years of flawless operation for me anyway.

[Bitsyncmaster]

If your reporting how you see the flashing light, it's great to get all the data you can provide. Also note if you have my fan relay. Been thinking about this problem and my fan relay may help. It will not bounce (make and break contact) like the mechanical relays. It also will keep the fans running when the AC is cycling.

[WelmoedJ]

As promised a report on my irregularly flashing Fan Fail light (Bitsyncmaster's new Fan and Fan Fail relays):

As I mentions I was to replace the original fans with low current, low noise 7 Ah (80W) versions.
Having done that I used new connectors, pins and sockets to connect the existing wiring to the fans.
I also made new 16 AWG ground wires and routed them directly to the ground bolts left and right on the crumple zone (radiator supports).

Result:
- No more irregular flasing of the Fan Fai warning light.
- Voltmeter needle again a bit higher on the scale (about two needle witdh from the amber line above the 13 V mark) while idling.
- When the fans start (e.g. A/C) there's a slight drop in the voltage while idling, no drop when driving.

I'm happy, now I can reliably use the A/C again.