E48 relay wiring

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Jp69
Posts: 17
Joined: Sun Dec 23, 2018 4:11 pm
ECU Model: No ECU

E48 relay wiring

Post by Jp69 »

I have an old e48 ecu and loom that I have just fitted to a c20xe vauxhall engine. I'm a bit stuck on what wiring to use for both the ecu relay and fuel pump relay. I have wired everything up temporary and works perfect. What size wire should I use for the relay wiring? Switched +12v, permanent +12v etc. Any help would be much appreciated cheers
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: E48 relay wiring

Post by stevieturbo »

Size of wire will depend on the load of whatever device you are powering with the relay

The ecu triggers the relay via ground, not 12v.

The ecu itself would not draw much current, and fuel pumps vary.
Jp69
Posts: 17
Joined: Sun Dec 23, 2018 4:11 pm
ECU Model: No ECU

Re: E48 relay wiring

Post by Jp69 »

Spoke to dta and was told that the ecu triggers the fuel pump relay via earth (pin 10 on ecu) which I have done and it works fine.
The ecu relay I have connected to pins 21,22,23,24 and 25 which I believe are for power to injectors, coilpack and ecu itself.
Both relays are 30a with a diode fitted, both 4 pin also. And are both connected to the battery vid 20a fuses.
It is running a standard vauxhall injection fuel pump if that makes a difference, but will be upgrading to a walbro 255 in the future
katana
Posts: 455
Joined: Sun Jan 27, 2013 6:08 pm
ECU Model: S60 Pro
Firmware Version: 29

Re: E48 relay wiring

Post by katana »

Have a look at the S series manuals - they have guidance on wire spec's. page 105 in S60 manual.
Alex DTA
Posts: 1622
Joined: Fri Feb 28, 2014 1:03 pm
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79

Re: E48 relay wiring

Post by Alex DTA »

Pins 21 to 24 are signal outputs, they shouldn't be connected to a relay

Pins 21 and 22 (if used) go direct to the injectors.
Pins 23 and 24 go direct to the coil pack.
Pin 25 only should be connected to the ignition relay.
Jp69
Posts: 17
Joined: Sun Dec 23, 2018 4:11 pm
ECU Model: No ECU

Re: E48 relay wiring

Post by Jp69 »

Hi Alex thanks for the reply. Without having the loom in front of me, I'm sure there was 2 thick red wires coming from what looked like pins 21-25 that broke off into a sub loom (round 2 pin connector) marked relays. I have connected both these to a 4 pin relay, along with a permanent earth, switched live and permanent live.
The fuel pump relay I've wired to the fuel pump, permanent live, switched live and the earth comes from pin 10 of the ecu.
The car starts and runs fine.
I think I'm going to use 17amp cabling for the wiring of the relays I.e switched live, permanent live (with a 20amp fuse) and also the earth.
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