K Series EU3 Engine Loom Wiring Diagram -
Updated/Corrected
Having
recently built a spare K-Series engine I had need to
make an engine wiring loom from scratch. Working from the published Caterham K
Series EU3 Wiring Diagram I found several problems:
i.
The diagram contains numerous errors, some of which are just irritating
(e.g. ECU plug pin layout is neither a front or rear view but a mixture of the
two) and some of which are serious (e.g. the VVC cam sensor wires are shown
reversed and the LT coil pack connections are shown swapped over between the
coil packs).
ii.
Wiring which is shown as being the same on all cars actually varies
between different examples. In particular the Main Relay in the MFRU is used in
some cars and unused in others, as discovered when some people found additional
wiring while implementing my K-Click modification.
iii.
No part numbers or sources are shown for any of the connectors. Although
many are standard series connectors, some such as the ECU plugs and engine loom
to injector loom headers are more difficult to identify. Rover part numbers are
now of little use - OEM part numbers are required.
iv.
No specifications are shown for wire sizes. This may not be important
when fault finding but are required when fabricating a new loom or replacement
sections for repairs.
v.
(Most of) the connector pinouts are drawn looking at the front face of
the plugs. when building a new loom I was mostly
inserting wires into plugs from the back, and therefore had to keep swapping
round all the pinouts in my head. It would have been much more useful if the
pinouts were shown looking at the plug from the wire side.
vi.
The diagram contains information relevant to all models, much of which
is not relevant to my loom. For my purposes it would have been nice to be able
to "switch off" the wiring for options which I did not have. In
addition the diagram shows discreet wiring which is not part of the loom, e.g.
battery and starter cables, and it would have been nice to have been able to
switch these off too.
I have therefore
completely reworked the wiring diagram to address all of the above and wanted
to share it back to the club membership as I felt others may find it useful. I
have done it as a Paint.NET project (free download for Windows here) with each of the options in a separate layer, so you can switch on and
off the options relevant to your car and get a specific customised wiring
diagram. I have also made flat .PNG versions of it, showing all optional
wiring, in two flavours (with or without the Main Relay wiring).
Download
Links:
·
Full Flat .PNG (With Main Relay)
·
Full Flat .PNG (No Main Relay)
To check
whether your car has the Main Relay wired in the MFRU, compare the wires connected
to the plugs on the MFRU (on top of the ECU) with this diagram - if you have an
extra Brown (or sometimes Brown/Blue or Brown/Pink) wire on Pin 8/8 like this
then your Main Relay is used (this allows the ECU to completely disconnect the
supply to the engine electrics such as injectors and coil packs and reduces
battery current drain through leakage).
i.
All of the known errors have been corrected. A VVC 160 engine wired
exactly as per this diagram certainly runs happily. If anyone does spot any
errors or omissions, please let me know and I'll be happy to try to keep this
up to date as a reference. Similarly there are areas of the diagram which do
not apply to my car, in particular the extra wiring for Apollo and Dry Sump
Stack systems where little detail is shown for connectors etc. If anyone is
able to supply me with more information on these, again I will update.
ii.
As described above, I have taken into account the differences in Main
Relay wiring.
iii.
I have tracked down OEM and part numbers for each of the connectors.
Using these I was able to source a complete set of brand new connectors. Please
be aware that with some connectors e.g. the multi-pin ECU plugs, there are
other connectors which look almost identical but have slightly different
terminal sizes etc. The part numbers shown are believed to be correct.
iv.
Wire colours and sizes are shown for every wire. For every single wire I
both took measurements off my loom or old looms which I stripped down, then
cross referenced the results with original Rover circuit diagrams. when building my loom I found it difficult to source wires
in all colour combinations on 0.5mm² and 0.75mm² sizes, so substituted 1.0mm²
wires for these. Although this may make the loom slightly bulkier that if the
original sizes were used, the number of redundant wires which I was able to
omit made up for this. The only issue was that clipping the back covers onto
the ECU plugs was a little tight, but manageable.
v.
On my diagram ALL CONNECTORS ARE
DRAWN VIEWED FROM THE WIRING SIDE, NOT LOOKING AT THE CONNECTOR FACE. This
was primarily because I drew the diagram for the purposes of constructing a new
loom and this was the most useful view for me, however it is different to the
convention (mostly) used by Caterham. It is at least consistent throughout.
vi.
PLEASE NOTE THAT THIS DIAGRAM
APPLIES TO EU3 K SERIES ENGINES ONLY.
The layers
available in the Paint.NET version are:
i.
"Background" - Plain white background. You will always want to
switch this layer on.
ii.
“Notes” - Notes, keys, legends and logos. You will always want to switch
this layer on.
iii.
"Common All Models" - As the name suggests, this layer
contains wiring which is common across all K EU3 engine installations. You will
always want to switch this layer on.
iv.
"MFRU Output Pin 8 Used" and "MFRU Output Pin 8
Unused" (ONLY SELECT ONE OR THE
OTHER) - These layers contain the two different Main Relay configurations
as described above.
v.
"EU2-Style IAT (No 4
Runner)" and "EU3-Style IAT (Within MAP)" (ONLY SELECT ONE OR THE OTHER) - These layers contain the two
different Intake Air Temperature Sensor configurations. The "EU2-Style IAT (No 4
Runner)" configuration is incorrectly described on the Caterham diagram as
being "VVC Models Only" and the "EU3-Style IAT (Within
MAP)" configuration is incorrectly described as being "Not VVC
Models". As far as I can determine, for EU3 engines only VVCs originally
destined for Pre-2004 MG ZRs had a separate IAT sensor on the lower inlet
manifold. I believe this was as a result of using up old stock castings from
earlier engines. If your engine has a green IAT sensor like this and this on
the lower inlet manifold AND IT IS
CONNECTED, you will want to switch on "EU2-Style IAT (No 4 Runner)", otherwise switch on
"EU3-Style IAT (Within MAP)" (NOT
both). WARNING: When I got my car it
had no sensor on the lower manifold, however it did
have an unused plug dangling where the sensor would have been. The ECU inputs
were wired to this (i.e. I was wired according to "EU2-Style IAT (No 4 Runner)") instead of
being wired to the combined IAT/MAP sensor. When I connected and OBDII scanner
up it showed an IAT of -40C and an IAT fault logged. The engine was permanently
in LOS (limp) mode with adaptive fuelling disabled. The engine fitted was
clearly not the one the car was wired for. I rewired the loom according to
"EU3-Style IAT (Within MAP)" and everything was happy. I mention this
because other people may find this or the opposite - an unused sensor on the
manifold, as older manifolds may be fitted to later engines, in which case the
sensor may be present simply to plug the hole but the engine will be using the
combined IAT/MAP sensor.
vi.
"VVC Mechanisms (VVC Only)" and "Cam Sensor
(Non-VVC)" (ONLY SELECT ONE OR THE
OTHER) - Switch on "VVC Mechanisms (VVC Only)" if you have a VVC engine,
otherwise switch on "Cam Sensor (Non-VVC)" which contains wiring
details for the 3-pin camshaft position sensor used on non-VVC engines (which
use a 2-pin camshaft position sensor)
vii.
"Emissions Ctrl (Non-UK)" - This layer contains details of
emissions control systems not fitted to UK models including the charcoal
canister purge valve and post-cat oxygen sensor. Only switch on this layer for
export models which do have these systems fitted.
viii.
"Shift Light (Supersport)" - This layer contains details of
the shift light fitted to Supersport models only. From what I can see, this was
implemented by reprogramming the ECU to turn on the AIR CONDITIONING at the RPM
limit, and the air conditioning output of the ECU was then cunningly wired to
the shift light.
ix.
“Stack Dashboard” - This layer contains details of the additional wiring
for models using the Stack dashboard only. As mentioned above, some additional
systems were not implemented on my car so I was unable to add much detail over
and above that on the Caterham diagram.
x.
"Oil Temp Sensor (Apollo & Dry Sump)" - This layer
contains details of the additional oil temperature sensor fitted to models with
Apollo and dry sump oil systems. As mentioned above, some additional systems
were not implemented on my car so I was unable to add much detail over and
above that on the Caterham diagram.
xi.
"Injectors & Coils (Sub Loom)" - This layer contains
details of the separate injector and coil pack sub-loom. This will be present
on all cars but I included it as a separate layer as I wanted to be able to
produce a diagram for the main loom only. Switch this layer on or off according
to whether you want to show the sub-loom.
xii.
“Yazaki Type Sub Loom Connectors” - This layer contains details of the
Yazaki type connectors used on the ignition and injection sub-loom on some
vehicles. If your injectors and ignition coils are on separate sub-looms with
separate connectors into the main engine loom, switch this layer on. If your
injectors and ignition coils are on a single sub-loom with a single locking
connector into the main engine loom, switch this layer off.
xiii.
"Discreet Wires (Not In Loom)" - This
layer contains details of discreet wires which do not form part of the main
wiring loom, such as alternator, battery and starter connections. As above,
this will be present on all cars but I included it as a separate layer as I
wanted to be able to produce a diagram for the main loom only. Switch this
layer on or off according to whether you want to show external wiring.
I hope this
is of use to people. Please feel free to feed back comments and corrections
which I will endeavour to incorporate into the diagram as and when I get the
time.