I am a car mechanic, and I am working on an XJ12, 5.3 1984 which does not inject at the moment.
It has a DAC3062 controller. The problem is that pin 18 Engine speed is not connected and hanging loose. I am not sure where to connect it to. So far I understood it should be connected to the amplifier.
The amplifier is mounted in front of the engine bay above the water cooler and not on the engine like I saw elsewhere and has 6 wires.
3 to the hall sensor, 2 to the 9BR Y47229A Ignition Ballast Resistor Block and one to the ignition coil.
I might add we got the car in a not running condition with the task to repair the ignition, which we did.
So there might be a mismatch between the ignition and injection system.
In principle, the ECU uses ignition pulses to āreadā engine rpms, of course - triggering injection, all injectors, one every engine revolution. As the amplifier alternately āmakesā
and ābreaksā coil ā-ā ground, the usual set-up is to connect the ECU #18 to coil ā-ā instead of a separate connection to the amplifier itself. However, different ign amps were used, and my manuals are not clear - a resistance may be required and the #18 might then be connected to the resistor packā¦
Obviously there is no ready place for the disconnected wire to connect to the amp or resistor packā¦?
Others may know better than me - but welcome on boardā¦
It might help to properly identify the car and ignition system. It sounds like you have a āPre-HEā car with the older Lucas Opus ignition (as opposed to Lucas CEI) which would make the car older than 1984; probably more like 1980-ish.
Along those line it would then have the older fuel injection system, perhaps D-Jetronic?
Iām still on my first cup of coffee. But this might help?
Doug, Your info is pretty dang close. Thereās an archive post from waaay back on July 2000 on the XJS forum titled āECUā. Within that post, Mike Morrin collected a list of ECUās and the year vehicle, etc. His info indicates DAC3062 is a 6CU used in 1981 in the HE engine with Lucas CEI and no O2 sensors. SD Faircloth
Which would be in conflict with (what seems to be) the OPUS ignition the OP seems to have.
With the last 6 digits of the VIN and/or build date we can probably begin narrowing-down what you have and then, hopefully, refer to the correct service manual info and wiring diagrams
Hello,
the white wire should go to terminal - of the ignition coil. But neither with 6-8 ohms resistance nor directly do we get the signals to the injectors.
If there is loose contact from plus, the injection nozzles open once time.
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Does that mean that the ālooseā wire is white, Claus?
Which would be odd; in Jaguar color logic white is a circuit powered with ign āonā. Ie, white wires are supposed to deliver power to āsomethingā. The ānormalā color for amp/coil to ECU is white/black - where the /black generally denoting something connecting to groundā¦
This is a general ECU feature; as ignition is turned āonā, powering up the ECU, the injectors click onceā¦
As Doug says; getting the appropriate wiring diagram, or āallā diagrams relating to the V12, seems relevant - though not that it seems easyā¦
As an aside; in āmostā cases, being rather long the relevant connection from the ECU amp or wherever, is split by a connector āmidwayā. Any chance that the loose wire is disconnected from a similar connector somewhere in the wiring loom? The type of connector on the loose wire may be a clueā¦?