QuestionQUESTION: I have a 97 disco, 4.0, gas burner that died while driving 35 mph, just died instantly. I checked OBD and no codes. I have fuel pressure but no spark, compression is around 160 psi. I checked the crank sensor and was not getting any AC voltage while cranking, so I replaced it with a new one, still no spark. Does the immobilizer need to be reset after working on it or do I need to check else where? I've been working on cars for 23 years so I know my way around them and any help would be appreciated.
ANSWER: Hi Tim,
did you check for blown fuses? My first thought was coilpack failure. Here's a test that may help (thanks Dave):
"First you need to identify and check the offending circuit. Does the vehicle crank and not fire, or does it not crank over?
If it cranks but does not fire, then the problem is in the fuel solenoid circuit on a Tdi, or ignition/fuel on a V8.
Take a digital voltmeter (DVM) and check if the fuel solenoid (Tdi) or ignition coil/fuel pump (V8) has a 12 volt supply to it by connecting the meter to the relevant blade connector and earth and turning the key to position 1 (on). If there is a 12 volt supply to the circuit, then the fault probably lies elsewhere. (Note that a dry joint may not always provide a perfect break in the circuit; on my own vehicle, it caused a voltage drop at the coil which was only apparent once you started cranking. As a result all appeared OK at rest, but when you tried to crank there was no spark. As I "knew" there was power to the coil, I didn't look at this any further, so it took rather a long time to find out that the power consumption when cranking was causing a voltage drop at the coil, which in turn caused the ignition amplifier module to cut out).
The connectors you are looking for are:
- The small blade connector on the back of a 300Tdi fuel pump, down by where the injector pipes come out
- The + connector on the coil of a V8
...if it's the V8 fuel pump you're on your own as I haven't had that out!
If there is no voltage at the circuit in question, then the next stage is to take the spider unit out - jump down to Repair.
If it does not crank, then the problem is in the starter circuit (Tdi or V8, much the same on both). Take the thin lead off the starter solenoid on top of the starter motor, and stick a DVM between it and a good earth. Turn the key to position II (start). You should get 12 volts across the meter. If you do, then the fault is most likely with the starter motor ... but to be sure, put the lead back on, stick the meter probe into the back of the connector, and operate the starter again. If the voltage is still present but the starter isn't doing anything, it will be the starter. If the voltage does not appear under load, it will probably be the spider unit. Time to take the dash out."
let me know if you need help with the spider...
Best of luck,
JohnMc
---------- FOLLOW-UP ----------
QUESTION: I have 12 volts at the coil and fuel pump runs, all fuses are good. There is no pulse at inj. plugs or spark out any coil. How do i tell if the immobilizer is on, or tell if the cam sensor is working(and where is it)? The motor spins over fine and the timing chain is good with no slack.
AnswerTim,
I read somewhere that it could be the lead from the coilpack to the ECU. This wire can weaken due to engine heat and cause this type of problem.
Immobiliser is on when you see a "red key" symbol on the dash when you attempt to start the engine.
The cam sensor is located at about the 2 o'clock position up above the oil filter (facing towards rear of Disco).
A LR owner wrote about a cam sensor problem, it "has a male to female plug and the female end goes up and outside of the male end creating a little 'cup' for the water to run into / collect in. Remove the bolt, clean the connection out with contact cleaner ... fill the connection with dielectric grease then invert the sensor and remount. When you invert it, the female end is on top and over the male end, all but ending the water ingress".
Here's the Rave data:
Crankshaft position sensor (CKP Sensor)
The crankshaft position sensor is the most important
sensor on the engine. It is located in the left hand side
of the flywheel housing and uses a different thickness
of spacer for manual and automatic gearboxes. The
signal it produces informs the ECM:
- the engine is turning
- how fast the engine is turning
- which stage the engine is at in the cycle.
As there is no default strategy, failure of the
crankshaft sensor will result in the engine failing to
start. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
Camshaft position sensor (CMP Sensor)
The camshaft position sensor is located in the engine
front cover. It produces one pulse every two
revolutions. The signal is used in two areas, injector
timing corrections for fully sequential fuelling and
active knock control.
If the camshaft sensor fails, default operation is to
continue normal ignition timing. The fuel injectors will
be actuated sequentially, timing the injection with
respect to top dead centre. Injection will either be
correct or one revolution out of synchronisation. The
fault is not easily detected by the driver. The fault is
indicated by illumination of the malfunction indicator
light (MIL) on North American specification vehicles.
Best of luck,
JohnMc
