What are symptoms of DME failure?

[Joss Walker]

Everyone talks about this but I don't know what actually happens to the car - can someone drop a brief description?

As you may suspect my S2 has failed to start, it hasn't been run for quite a while and the battery is good but when I turn the key nothing happens, doesn't even sound like the starter engages - is this a failed DME?

Thanks, as ever for your help

 

[944Turbo]

No starter motor is more likely an immobiliser or ignition switch issue, dme relay symptoms are more rough running and/or cutting out. From memory it energises sparks and fuel pump - nothing to do with cranking (or not)
Tony

 

[Joss Walker]

Damn!!

it only seems to have about 8 alarms/immobilisers fitted so this should be fun

 

[944 man]

Its two relays in one case. The first relay energises the DME when the ignition is turned on and the second relay energises the fuel pump when it is activated by the DME. The DME sends the command signal when the engine is spinning quickly enough on startup and it turns off the fuel pump when the engine speed falls below the minimum.

The relays can fail in a number of different ways, and they didnt used to be particularly long lived originally. The 993 prefixed part is better in this respect.

 

[Martin Sage]

Just replaced my DME relay Joss. But mine turned over ok but wouldn't start due to faulty relay not allowing fuel pump to work.
Frazer Part c£25 if you need one. Sounds like you may have other issues though [&:] Good luck

 

[dunc]

ORIGINAL: Martin Sage

Just replaced my DME relay Joss. But mine turned over ok but wouldn't start due to faulty relay not allowing fuel pump to work.

Identical here, no fuel pump on ignition or when turning over. Replacing the DME relay with a jumper fired the car up first time, now has a new relay in place.

Dunc.

 

[Diver944]

ORIGINAL: dunc

now has a new relay in place.

and I hope a spare in the glovebox for when it happens again several years down the line [8|]

Mne seem to last about 5 years and then all of a sudden the car won't start. The symptoms were it will turn over quite happily but not actually start.

 

[dunc]

ORIGINAL: Diver944
and I hope a spare in the glovebox for when it happens again several years down the line [8|]

Got the jumper in the glovebox, made a tidy job of that even if I do say so myself [8|]

Dunc.

 

[Mike_Pollock]

Joss, good news is that immobilisers dont usually affect the starter motor.

Do you get a click when turning the key?

If so, its probably the starter solenoid, if not, the starter itself.

 

[Joss Walker]

Thanks for all these comments - even though none of them tell me what I wanted to hear!

I'm going to get the RAC to come and try to start it in the first instance (I've been paying for years so might as well get some use from it) and they should give me some good pointers as a starter for ten!

 

[Veerzigzag]

good news is that immobilisers dont usually affect the starter motor

I have four cars with immobilisers and in all four the immobiliser disables the starter motor too. So the dash lights come on but the starter does not turn.
Joss does not say if the dash lights come on or not - do they?

 

[Joss Walker]

All the dashboard lights and other electrics seem to work OK, but the car is back under its bubble right now so I will get it out later today and have a more thorough inspection.

 

[944Turbo]

ORIGINAL: Veerzigzag

good news is that immobilisers dont usually affect the starter motor

I have four cars with immobilisers and in all four the immobiliser disables the starter motor too. So the dash lights come on but the starter does not turn.
Joss does not say if the dash lights come on or not - do they?

Indeed, a multipoint immobiliser should immobilise multi points, - fuel pump, starter, ignition circuits - they often don't but that is laziness on the part of the installer.
My old Nissan Patrol (Diesel) had to have a multipoint immobiliser (single point not acceptable) for the insurance, one was fitted and certified by an approved installer and when I removed it several years later they had immobilised the starter and nothing else - but then it is tricky to immobilise a mechanical fuel pump. Not impossible as the car stops when you turn the key to off but obviously too hard for the alarm 'expert'

Tony

 

[1540phil]

ORIGINAL: Joss Walker

Everyone talks about this but I don't know what actually happens to the car - can someone drop a brief description?

As you may suspect my S2 has failed to start, it hasn't been run for quite a while and the battery is good but when I turn the key nothing happens, doesn't even sound like the starter engages - is this a failed DME?

Thanks, as ever for your help

Mine won't turn over either!

 

[944Turbo]

If the starter clicks but doesn't spin it is the solenoid, I revived one for several months while sourcing a replacement by filling it with contact cleaner spray - once removed from the car there is a hole you can spray through. It was still working when I took it off the car but I swapped it for a much newer one just in case.
Tony

 

[Joss Walker]

Car started fine at the weekend - I haven't done anything to it, just thought I would try it again to see if the starter solenoid worked as per Tony's advice. So not a scooby's what's up with it, we'll just have to see if it happens again!