Roadster ESP Water Ingress

Imagine that, water ingress in a Roadster. Strange how an exterior controller is less likely to be affected by water ingress than a controller inside of the car.

ABS Unit

On the Roadster, the ABS pump is easy to access. You open the bonnet and remove the front boot bucket.

It has 6 pipes, 1 sensor and 1 multipin connector.
The outer 2 pipes on the top of the unit go to the brake master cylinder.
The remaining 4 pipes go to each wheel. The sensor is for ESP brake pressure.

On the back of the pump is the ESP controller. Grab the locking lever…

…and flip it up.

The multipin connector can now be pulled from the ESP controller.

1 of 3 things will happen. Either the wire surround grommets or the wire blanking grommets in the plug will fail and let water passed, or the perimeter seal of the plug will fail and let water passed. Rubber doesn’t stay malleable for ever, that’s what you can only use a condom a few times before you trade it for a refurbished one.

Once the water has made it into the socket, 1 of 3 things will happen.

1 – Water will cause a short circuit between connections that should be connected.
2 – Water will seep passed the pins in the socket of the ABS controller and it’ll fill up, causing more short circuits.
3 – Water will corrode terminals in the connector, eventually causing bad or missing connections.

This is what happened to Martin H who sent this photo. You can see that corrosion has turned the copper contacts into the finest quality green dust.

Symptoms

You may have 1 or more of these signs.

1 line on the speedo (CAN Bus fault).
Rev counter drops to 0 when the brake is applied.
Will not select gears.
Flashing traction control light /!\
Fuel gauge and coolant temperature gauge flashing.
Power loss whilst driving with traction control light showing.

Fix

This really depends on the damaged caused.

1 – If water has got into the pump controller, you’ll need a replacement ABS unit. As far as I know, you can fit a 2nd hand unit.

2 – If water has corroded the pins of the unit or the terminals of the plug, you can use vinegar to clear up the area. You can flood the affected area and leave it or agitate it with a tooth brush, interdental brushes, cotton buds etc. Clean up the area with electrical contact cleaner spray.

3 – If the pins of the ABS unit have corroded to nothing, you’ll need a replacement ABS unit.

4 – If the terminals in the connector have corroded beyond repair, you have 3 options.

A – Remove the damaged terminals with a terminal remover and soldering in replacements.

B – Buy a 2nd hand wiring loom and replace the entire affected loom or splice it into the existing loom or remove some of the good terminals and swapping them for the bad ones and splice those in.

C – Buy a repair loom from smart (assuming it exists and available), It’ll be a connector with a length of wire connected to each terminal. Again, you’ll have to splice it in.

Double Protection

Now, there’s no point in doing all of this work just to let it happen again some time down the line.

So, it’s a good idea to put dielectric grease into the plug and socket. If you take up all of the air in the connector, water can’t displace the grease. Don’t over-pack the socket as the seal of the connector could push the grease into the connector and possible push some of the rubber bungs out where there are no cables.

Retrospective Fix

Of course it’s better to not have the issue in the 1st place so it’s a good idea to put dielectric grease into the plug and socket to protect the pins and terminals from water ingress and corrosion. Don’t over-pack the socket as the seal of the connector could push the grease into the connector and possible push some of the rubber bungs out where there are no cables.