Hi all,

 

my 68 plate transit custom limited panther 2.0 ecoblue has no rear brake lights, been like this for ages haven’t drove it for weeks due to this, I’ve taken it to 3 garages now and they can’t find the problem. 
 

my cruise control also stops working once I get to 30-40 mph.

gave it to a friend who is a mechanic late yesterday afternoon and he was on it for hours, originally plugged it in and had a code for a faulty brake light switch, got a new one, fitted it and nothing. He then tested every fuse and couldn’t find any that were blown, all had continuity. 
 

starting to drive me mad I need to get this sorted asap. Does anyone have any ideas?

 Also been looking online for correct fuse box locations they all seem to be different to mine, only one I can find that matches is the fuse box under the bonnet. I’ve been told if a fuse has gone it will be under the steering wheel but every picture/diagram I’ve came across online looks completely different to mine

 

Any help is appreciated 

 

thanks so 

 

So did your friend check for live at the switch. The yellow red wire? 

After the switch, the feed goes into the body control module. Your friend should check for live from switch to bcm , and output from bcm to brake lights. 

Or first, check for corrosion at the bcm connectors. Bit of a fiddle to get connectors unplugged but once done a torch and mirror to check the bcm pins and connectors. 

40 minutes ago, iantt said:

So did your friend check for live at the switch. The yellow red wire? 

After the switch, the feed goes into the body control module. Your friend should check for live from switch to bcm , and output from bcm to brake lights. 

Or first, check for corrosion at the bcm connectors. Bit of a fiddle to get connectors unplugged but once done a torch and mirror to check the bcm pins and connectors. 

Thank you for the reply mate,  I’m not sure if he checked that, I had to go and do a job and left the van with him.

 

I’ve currently got all the inners took out and having a look myself, have some continuity & voltage testers. I see the brake switch cables go up behind the back of the bcm, not sure if it loops back down to the bcm? I can’t see any further up it’s extremely tight. Where would i test between from red/yellow on the switch and the bcm? 

Also what’s the trick to getting these clips out? Extremely tight I thought there were ones with tabs on the side you squeeze and then the white handle lifts up? 

Lots of evidence of water ingress in and around those connectors 🙁

Lift the handle fully back and it will eject the connector from the socket.

24 minutes ago, unofix said:

Lots of evidence of water ingress in and around those connectors 🙁

Lift the handle fully back and it will eject the connector from the socket.

 

I have been trying that for the last hour and a half 😂🤦‍♂️ it is so tight it won’t budge, even tried prying with a small flat head.
 

do you think this could be a relay issue? I also have no hill assist & no cruise control 

I think you have to press down the centre black section to release the white handle?

4 minutes ago, TomsFocus said:

I think you have to press down the centre black section to release the white handle?

Worked instantly 😂 absolute legend thank you 

Red yellow is the permanent feed to the switch. Check at that connector for 12v.red yellow.

If that ok and you have replaced switch, go to the connector you have unplugged on bcm and check for 12 v at pin 1 violet white with brake pedal pressed. 

My gut feeling it will be water ingress/ corrosion at the connector. The connector to look at is the lower left corner. 

On 2/15/2025 at 6:55 PM, iantt said:

Red yellow is the permanent feed to the switch. Check at that connector for 12v.red yellow.

If that ok and you have replaced switch, go to the connector you have unplugged on bcm and check for 12 v at pin 1 violet white with brake pedal pressed. 

My gut feeling it will be water ingress/ corrosion at the connector. The connector to look at is the lower left corner. 

Thanks for the great reply mate.

 

i have attached a photo of the pins after taking the plug out, only corrosion I could see was the big pin at the top left. 
 

cleaned it all up with electrical cleaner and still no joy, no 12v at the switch also 

Houston you have a problem !!

That is clear evidence of water ingress in to the BCM. At the very least you are going to have to fully remove the unit and open it up. It's very likely that the circuit board will have signs of greenish corrosion and damage to the copper tracks and even the components.

Sometimes if caught early enough, a good scrub of the circuit board with IPA and a bit touching up of tracks and joints with a soldering iron can save the BCM. Otherwise I'm afraid you're going to need to find a replacement.

11 minutes ago, unofix said:

Houston you have a problem !!

That is clear evidence of water ingress in to the BCM. At the very least you are going to have to fully remove the unit and open it up. It's very likely that the circuit board will have signs of greenish corrosion and damage to the copper tracks and even the components.

Sometimes if caught early enough, a good scrub of the circuit board with IPA and a bit touching up of tracks and joints with a soldering iron can save the BCM. Otherwise I'm afraid you're going to need to find a replacement.

***** hell what a nightmare! I have checked all other plugs & pins and a lot of corrosion on the pins, the one in the photo I attached probably is the best looking out the lot!😂

All spilt coffee from the cup holder directly above, surprised it’s not at least got a cover over it seeing it contains fuses and all these plugs. As of now I’m only down brake lights, hill start and cruise control over a certain speed. 

just wanted to check I cannot potentially damage any vital internal electrics by disconnecting all these plugs and removing the whole unit? Do they need to be plugged back in or out in a certain order or not? Am I right in saying after installing the bcm back in you plug all plugs in first and then the main power plug (black plug at the very bottom right hand side) 

 

appreciate all the help thanks a lot 
 

 

1 hour ago, Dixy10 said:

just wanted to check I cannot potentially damage any vital internal electrics by disconnecting all these plugs and removing the whole unit? Do they need to be plugged back in or out in a certain order or not? Am I right in saying after installing the bcm back in you plug all plugs in first and then the main power plug (black plug at the very bottom right hand side) 

BEFORE removing any connectors you should really disconnect the negative lead from the vehicle battery and keep it out of the way of the battery negative terminal. As regarding causing damage to any vital electrics, I'm afraid you already have. The Body Control Module is one of the main 'computers' of the vehicle. All you can do is hope for the best, and plan for the worst !!

The BCM may be able to be saved. You will need to get at least a 1 litre bottle of Isopropanol Alcohol (IPA) and a good strong small paint brush (or toothbrush). Give it a good clean and let it dry. Inspect it once clean and look for any corroded or damaged components.

https://www.amazon.co.uk/Trade-Chemicals-Isopropanol-Alcohol-99-99/dp/B08FJ74J22/ref=asc_df_B08FJ74J22

No 12v at the switch, then you need to check the fuse f18 10amp to see if it's blown or 12v at the fuse. 

Aux fuse box( to the left of steering column) 

 

2 hours ago, unofix said:

BEFORE removing any connectors you should really disconnect the negative lead from the vehicle battery and keep it out of the way of the battery negative terminal. As regarding causing damage to any vital electrics, I'm afraid you already have. The Body Control Module is one of the main 'computers' of the vehicle. All you can do is hope for the best, and plan for the worst !!

The BCM may be able to be saved. You will need to get at least a 1 litre bottle of Isopropanol Alcohol (IPA) and a good strong small paint brush (or toothbrush). Give it a good clean and let it dry. Inspect it once clean and look for any corroded or damaged components.

https://www.amazon.co.uk/Trade-Chemicals-Isopropanol-Alcohol-99-99/dp/B08FJ74J22/ref=asc_df_B08FJ74J22

Regarding damaging vital electrics do you mean because of the corrosion that is there already? Or me removing the plugs?😂 
 

So if I disconnect the negative lead on the battery and keep out of the way, I would be ok to remove all plugs and bcm and then give it a clean with the IPA? 
 

thanks for the help 

The corrosion will be the cause of possible damage. 

Clean with IPA you can get the circuit board completely wet with it.