Lucas AB17
ECU Ignition
- If you have established
there is no spark at the plugs before doing anything else
check the cam belt isn't broken -- if the belt is broken
rotor arm won't be turned by the camshaft :-(
- Carefully examine the
coil, distributer cap and leads for cracks or signs of
damage.
- The distributer cap and
rotor arm on OHC Rover engines tend to suffer from
neglect as the cap is difficult to remove for cleaning,
the rotor arm on early models also tends to crack
particularly if it is the type with a metal insert, later
type OEM rotor arms are often marked with a
dab of red paint.
- Due to its location often
on high mileage Rovers the inside of distributer cap may
be contaninated with of oily residue. If this is the case
the cap may be carbonised and need replaced. I always buy
OEM rotor arms but I prefer non Rover/Lucas distributer
caps as the aftermarket types are retained by more
convenient slot headed screws, The oil seal inside the
distributer is very easy to renew and this should be done
at the earliest opportunity and the crankcase breather
cleaned at the same time.
- After looking for any
obvious broken connections or dampness , turn the engine
over on the starter; the tachometer needle should give a
slight kick as the engine is turned over. If it doesn't
this points towards a low tension fault. If the needle is
kicking this would tend towards eliminating the ECU
and crankshaft angle sensor as a possible cause ;-)
- One possible low tension
fault is a blown fuse, unlike cars built in earlier eras
modern Rover & Austin-Rover Group cars have the
ignition fed through a fuse; on any 80s and 90s Rovers I
have worked this fuse is located in the internal fuse box
below the dash and is usually one of the fuses near the
top right of the fuse box.
- Even if the needle kicks
check 12 volts is getting to the coil via the green
wire.
- Put a multi meter set to
the 20 volts dc scale between the terminal
connected to white/black wires on coil and earth
when the car is turned over on the starter you should see
voltage rising and falling as the ECU pulses the coil to
ground. A failure on this test points towards connection
or ECU problems.
- Check that the 12 volt
power via the green wire to pin 9 of the ignition ECU is
getting battery while engine is being cranked.
- Check the crank shaft
angle sensor (CAS) voltage output at cranking speed, also
check the resistance and examine the cable and plug for
damage, see page on CAS for full details.
- If CAS output looks OK
check very carefully all the connections to the ECU,
particularly the earth grounding through the black wire
to pin 12. If this should show a voltage of more than 0.2
volts when cranking use a "Scotchlok" connector
to tap into the wire and run an earth straight to the
battery -Ve terminal.
If after working through
this check list there is still no spark at the plugs the evidence
would tend to point to either an Ignition ECU or Ignition Coil
fault, this will soon be covered in detail in another section.
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