Board logo

ECU repair
RedAvon - 2/9/19 at 10:27 AM

Hi,

Does anyone here offer an ECU repair service, or has recommendations for a company?

2002 Mazda Mx5

Thanks
Ian


obfripper - 2/9/19 at 01:01 PM

I use BBA-reman and Actronics at work, I've looked in the Actronics catalogue Mx5 is not listed (but they may still repair), BBA do list a couple but not all variations, but have some listed that are part number only so may be worth checking.

They both charge 35-50 to test, and usually approx 200 to repair inc test fee.


Dave


perksy - 2/9/19 at 07:48 PM

I've used ATP Electronics and they were good

www.atpelectronics.co.uk


RedAvon - 2/9/19 at 10:32 PM

Thanks for your helpful suggestions guys.

Perksy, this is the outcome of my previous post that you replied to, it wasn't the cam or crank sensors but water in the footwell up to the ECU connectors. Even though I checked the carpets were dry several times, they are plastic backed and didn't show any sign of damp from above.

Thanks again.
Ian


perksy - 3/9/19 at 06:26 AM

Thanks for feeding back

Water and ECU's don't mix sadly

I'm guessing there'll be condensation within the ECU itself


40inches - 3/9/19 at 08:17 AM

Would this be any good? eBay Item


RedAvon - 3/9/19 at 10:53 PM

Thanks both,

I dried out the ecu board in rice for 24hrs and used the hair dryer on connections and the pcb followed by switch cleaner etc but I think it's gone........ That's why I was getting weird readings on the sensors, as the terminals were shorting on the ecu, although the water level didn't reach the pcb itself.

40" thanks for the heads up on the eBay item, definitely a big saving on an ecu repair. I will check out compatibility tomorrow.

Will let you know how it goes - and where the water ingress is when I find it.

Cheers


RedAvon - 9/10/19 at 09:11 PM

Just an update for info.

Sent the ECU to ecudoctor in Plymouth and it tested ok, which saved the repair cost. Was very impressed with ecudoctor services, called me personally to explain and offered advice so I can recommend.

Cleared out internal roof channels but water still coming in. New sills have been fitted by previous owner so still need to ensure drain holes are included, or could be grommets in firewall.

Still no start. I've checked fuel pump relay is operating ok off car but ECU is not dropping the 12v on the relay coil to switch it on. Also found the ECU is not receiving a drop in voltage from 12v at switch-on to immobiliser pin during cranking. However the immobiliser light is coming on dash and then extinguishing ok. I am wondering whether the water on the ECU pins has lost the handshake code between immobiliser and ECU? Maybe I need to reset a code somehow between immobiliser and ECU?

I've managed to get a wiring diagram and worked out all the pins on the ECU connectors so hopefully it's just a matter of time to find what is going on.

Cheers
Ian


obfripper - 9/10/19 at 10:03 PM

I've had a quick glance at the wiring diagrams,there should be a switched live (from the main relay output) shared to 2 pins (30 and 86 on a euro type relay) on the fuel pump relay, the ecu switches the earth (pin 85) to activate the fuel pump.
If there is not 12v at the fp relay coil with ignition on, the first thing is to check the main relay. My wiring diagrams don't show full wiring for the main relay, but the control wire is the relay coil earth side so is likely to be activated by a control unit like the immobliser or body control unit.

Dave


RedAvon - 11/10/19 at 10:57 AM

Thanks Dave for checking this out.

I've now checked both the main and fuel pump relays off the car with a separate power supply (and their covers off for good measure ) they are both operating fine both mechanically and electrically.

On the diagram i have there is a white/blue wire to one side of the fuel pump relay coil which is fed from the main relay and 30A fuse. The red/white wire on the other side of the FP relay coil is at 12v ignition on and stays at around 10v when cranking. I think this should be pulled down to 0v to operate the relay. This red/white wire goes to the data link connector in the engine bay and the immobiliser system via pins 2m and 3s on the ecu.

So I am thinking that the immobiliser isn't telling the ecu to switch on the fuel pump. The car cranks over and the immobiliser tell tale on the dash does extinguish rather than flash. I had read that later models don't crank the starter to prevent the car being jumped on to a trailer in first gear. I'm not sure what a later model is, this is late 2002 Trilogy.

I will try to establish a reset for the immobiliser or work out if it is that which is the problem and send any updates.

Many thanks
Ian


RedAvon - 26/10/19 at 06:57 AM

Hi,

Just closing this out. It was the crank sensor in the end. Previous owner did not use a shoulder bolt through the mounting plate and it looks as if the crank lobes fouled the sensor, slowly wearing away the sensor face.

Thanks for your help, I learned a lot about the electrics on an mx5 that's for sure !

Ian