Hazard Switch issue

cjj · Feb 21st, 2021, 15:31

Hi all,

Had an issue with my Euro3 where the battery went dead earlier this year due to having no need to use the car. When I reconnected the battery, the brake lights were intermittently haunted (coming off and on independently and then being stuck on).
I whipped the CEM off and found a little corrosion on the smaller scuttle-side connector, but cleaned it all off and put it back on.

Since then, the brake light issue is resolved, but the hazards came on straight away. I scanned and got a CEM-8F05, which wasn't on before, but disconnected the switch and bought another used one.
That made no difference - the hazard switch, essentially doesn't worked at, but it turned them off so I left it parked without the hazard fitted.

Everything else works fine.

The other day, I had a knock on the door as the hazards were going again. I took the CEM off again and had a look, but no visible issues are there.

I get resistance between the black and yellow/white with the battery disconnected and no switch fitted. The switch itself also has this, so seems normal. There is no resistance between either wire and the solid yellow one. The switch suggests this should only occur when pressed.
The switch seems to not have an on/off position, so I assume it's software controlled.

The lights do randomly start and stop with no real trigger.

I've tried the battery reset to discharge the capacitors, but nothing. I've also disconnected the alarm siren to rule out that doing anything unusual.

I feel like I've ran out of options other than to send off the CEM, but I'm feeling like it's worth cutting my losses before that. I can't really see anything else when searching, but I've not got any other faults or codes on any module, or any other symptoms.

Does anyone have any other ideas/suggestions?

Baxlin · Feb 21st, 2021, 18:31

Sorry I can’t help, but I have a similar problem on my car, so I’m very interested in any advice too..

Thanks

SwissXC90 · Feb 22nd, 2021, 07:22

if the hazard lights randomly start and stop when the hazard switch is disconnected, then you have further corrosion issues in your CEM

Send it off for repair

Feb 21st, 2021, 15:31	#1
cjj Member Last Online: Apr 8th, 2022 11:13 Join Date: Nov 2014 Location: England	Hazard Switch issue Hi all, Had an issue with my Euro3 where the battery went dead earlier this year due to having no need to use the car. When I reconnected the battery, the brake lights were intermittently haunted (coming off and on independently and then being stuck on). I whipped the CEM off and found a little corrosion on the smaller scuttle-side connector, but cleaned it all off and put it back on. Since then, the brake light issue is resolved, but the hazards came on straight away. I scanned and got a CEM-8F05, which wasn't on before, but disconnected the switch and bought another used one. That made no difference - the hazard switch, essentially doesn't worked at, but it turned them off so I left it parked without the hazard fitted. Everything else works fine. The other day, I had a knock on the door as the hazards were going again. I took the CEM off again and had a look, but no visible issues are there. I get resistance between the black and yellow/white with the battery disconnected and no switch fitted. The switch itself also has this, so seems normal. There is no resistance between either wire and the solid yellow one. The switch suggests this should only occur when pressed. The switch seems to not have an on/off position, so I assume it's software controlled. The lights do randomly start and stop with no real trigger. I've tried the battery reset to discharge the capacitors, but nothing. I've also disconnected the alarm siren to rule out that doing anything unusual. I feel like I've ran out of options other than to send off the CEM, but I'm feeling like it's worth cutting my losses before that. I can't really see anything else when searching, but I've not got any other faults or codes on any module, or any other symptoms. Does anyone have any other ideas/suggestions?

Feb 21st, 2021, 18:31	#2
Baxlin Old Rocker Last Online: Yesterday 11:35 Join Date: Dec 2016 Location: Tring	Sorry I can’t help, but I have a similar problem on my car, so I’m very interested in any advice too.. Thanks __________________ Just my opinion, please don't shoot me if it doesn't match yours! 2011 C70 D3 (now sold)and JZR 3 wheeler

Feb 22nd, 2021, 07:22	#3
SwissXC90 Premier Member Last Online: Mar 20th, 2024 18:26 Join Date: Jan 2016 Location: Cross Country	if the hazard lights randomly start and stop when the hazard switch is disconnected, then you have further corrosion issues in your CEM Send it off for repair __________________ XC90 R-Design MY2009, Black Sapphire Metallic. HP-Sound, RSE, Nav, Tel, ParkingCam, BLIS, ParkingHeater, RestHeat, Removable Towbar, Summer: CRATUS 20x8 on Pirelli Scorpion Zeros 255/45, Winter: NEPTUNE 17x7 on Continental WinterContact 4x4 235/65.

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