S3 8P 2007 Engine Relay issue

[MWright]

Car has been scanned through VCDS and shows an engine relay related problem - I also have a 'anti-theft' switch which put the car in limp mode if not switched off before ignition.

The above switches an earth to a relay in the engine fuse/relay box.

I have seen different relays used in A3's and S3's, are there a standard set of relays? As i was tempted to by a 458 relay as this relay may not be operating correctly for it's intended purpose and that it works alongside this switch.

When I take this wiring out the car still remains in the limp mode with the EPC and EML lights lit.

Also if i leave the switch off/unarmed then it'll drain the battery if engine isn't running.

Any help is welcome.

Thanks Mat.

 

[Marek196c]

get rid of "switch" so you will be sure that isn't the problem, on side of both you should get the specs of them, if they are equal in terms of volt and amps shouldn't be any problem, however if you're no expert better leave it as is and buy another 433.

 

[MWright]

I've removed the wires of the switch and the car stills behaves as though i haven't switched the switch either it's the wrong relay or the relay is knackered because it has ground passing through a part that shouldn't. I believe the pin that is grounded should be grounded after the ignition it on - that's why i believe it's the wrong relay.

Yeah i could buy another 433, I've just seen many more photos with 458 in that place so I'll check the diagram for each to find the differences.

I'm handy enough with a multimeter.

 

[Marek196c]

they are 4 or 5 pins? so in witch state that pin should be before is on "ignition on"? if high (voltage appied) check where that pin was going, could be some fuse that cause of short circuit burnt, or some electronic component that fcked up. Anyway if you got still the invoice from that switch or know where it was done (if wasn't you to do it) just claim it and ask to resolve it for you.

 

[MWright]

they are 4 or 5 pins? so in witch state that pin should be before is on "ignition on"? if high (voltage appied) check where that pin was going, could be some fuse that cause of short circuit burnt, or some electronic component that fcked up. Anyway if you got still the invoice from that switch or know where it was done (if wasn't you to do it) just claim it and ask to resolve it for you.

458 is 5 pin.

I've also found out from @mjr901 that I have the wrong relays in the bay from standard spec.

I'm wondering if I'd need to replace all the relays or whether it's possible to replace just the one.

 

[Marek196c]

if you got the possibility to check the pinouts (probably all/most of them will got the same pinouts like pin 1 is Vcc, pin 2 is signal etc..) and maximum operating Ampere you can compare them. Or just get to local scrappy and get all of the right ones at once for 10 quids probably.

 

[MWright]

458 is 5 pin.

I've also found out from @mjr901 that I have the wrong relays in the bay from standard spec.

I'm wondering if I'd need to replace all the relays or whether it's possible to replace just the one.

So after I had realised the relays were not the same as spec'd.

I have now changed these to the above

458
100
167

Now there's no EPC light without grounding a pin on one of the relays. I'm yet find if there's any battery drain, as previously it could be drained if I left one of the relays pins grounded.

The incorrect relays was causing the MIL shown in VCDS.

I'll report back in a few days and hopefully all will be well.

Sent from my HTC 10 using Tapatalk

 

[MWright]

So the EPC and EML haven't made an appearance which is great.

One issue that threw me which also happened when I had the old relays in, when turning the key to start the car all power is lost much like the ECU goes in some protection mode. I have to reseat the engine relays for power to be restored then it may start or cut power again.

Only thing had me thinking it a loose wire on the starter motor as it's asking for greater current due to poor connection. Any one have any ideas?

 

[Marek196c]

short on starter motor relay?

 

[MWright]

short on starter motor relay?

I'd guess removing the relays and fuses to check underneath for shorts. I think 458 is the engine related relay, unsure if that powers the starter. I fitted a new starter 9 months ago.

 

[MWright]

So around a week ago I removed the battery and engine relay holder. To sort the above issue where I believe it's shorting somewhere due to when turning the key to start to car shuts off and no power (electrical) until I reseat the relays or pull the battery for a few mins.

So after a bit of checking I had noticed a few wires are stripped near the same area - this could be the short running up to the engine relays.

So I cut them and resoldered the wires just incase they'd had a poor connection. I then wrapped the loom leading up to the relay and fuse box in electrical tape.

Also noticed some funky residue under the relay/fuse box near he pin connectors, where it looks like a liquid or the surrounding plastic had melted?

Since I had done all of the above the issue has not yet appeared again, so keeping my fingers crossed.

 

[ch1z64]

So around a week ago I removed the battery and engine relay holder. To sort the above issue where I believe it's shorting somewhere due to when turning the key to start to car shuts off and no power (electrical) until I reseat the relays or pull the battery for a few mins.

So after a bit of checking I had noticed a few wires are stripped near the same area - this could be the short running up to the engine relays.

So I cut them and resoldered the wires just incase they'd had a poor connection. I then wrapped the loom leading up to the relay and fuse box in electrical tape.

Also noticed some funky residue under the relay/fuse box near he pin connectors, where it looks like a liquid or the surrounding plastic had melted?

Since I had done all of the above the issue has not yet appeared again, so keeping my fingers crossed.

Hats off to you mate for sticking with it as many would have stuck it into a auto electricans by now.

 

[MWright]

Hats off to you mate for sticking with it as many would have stuck it into a auto electricans by now.

Haha cheers, I always prefer a dabble at anything myself even if it is a complete waste of time. With a multimeter in hand not much can go wrong.

Next up... cambelt and water pump.


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