for Code Display Procedure, please see:

AJ6 ENGINEERING's web page

AJ6 FAULT CODES AND IDLE SETTING / AJ6 Engineering

I found this great pic of the 4-valve protoype there.

 

Beg, borrow or steal another ECU to try?

I recall a similar problem with a series III Sovereign I had and it was a cracked earth pin on the ECU.

Just my 2c.

 

rc,

My previous post came in 2 parts. The 2nd one started a new page. Be sure you read what I wrote and view/read my 2 attachments found at the bottom of page 1.

https://www.jaguarforums.com/forum/x...t-start-52649/

It seems the XJ40 can diagnose faults in the engine management system, at least for the components with which we are now questioning.

 

rc,

I was looking through my JAGUAR XJ6 DRIVERS HANDBOOK and found the Fuelling Failure fault that should be displayed on your vcm if there is a, well, you know.

I drew a pic.

 

rcarpenter:
You and Trick have a good thing going - far more than I can contribute. But, it occurred to me to ask you if you have tried starting it in neutral. I think these cars are designed to start in Park or Neutral. If the car doesn't recognize you being in park, for example, because of a bad switch, maybe neutral?
Just a thought. Hang in there.
Scott

 

Thanks again,
I have made the decision that it must be that fuel is not being released into the engine, I was thinking about removing the fuel rail again, leaving the injectors plugged in and then cranking to see if it will spew fuel all over the driveway. All along I've just kept checking to see if the pump was getting fuel to the rail and assuming it continued into the engine.
Now the VCM does NOT show any error codes when you cycle it through like the owner's manual sys to. The only thing that repeats is "boot open" and "bulb failure" but no numbers are displayed.
Today I will go print your pdf and see if I can find an open somewhere.
Thanks,
Rex Carpenter

 

Hi Rex,

Hmmm ... no fuelling fault on the facia display.

Why not test the ECU and the VCM?

1. By this I mean try disconnecting (gingerly) the coolant temp sensor or the air flowmeter or the crankshaft sensor,
2. crank the engine,
3. stop energizing the starter but leave the key in the "run" position and
4. watch the facia display.

Now you should get the iso exclamation point (!) symbolizing Fuelling Failure, eh?

 

Here's where I'm at now Trick,
Yesterday I didn't touch the car (daughter’s softball game), but tonight I will try what you suggested. Last night I did read your fuel failure doc and it made a lot sense. Now I can disconnect the cps and/or the coolant temp sensor and give it a try. But I'm still confused on how to accurately check the fuel ECU. Also I found a ecu for $600 used, so that's better, but still falls under my "troubleshoot by replacement" method which quite frankly thus far has, well to put it politely, not worked too well.
Rex

 

Rex,

I'll keep my fingers crossed for you and your test session tonight.

BTW I've sent you a PM.

PS Congrats on becoming a fully fledged MEMBER of the forum (me, too).

 

R,

Here's a 1 pager on what Haynes has to say about "pulling the ECU" from an XJ40.



There is a pic of the ECU in place.

https://www.jaguarforums.com/forum/a...odules-112-pdf

 

Rex,
Any changes or news? How's it coming?
Scott

 

The saga thus far is;
After all the troubleshooting since February I decided it was not getting fuel through the injectors. I have had many e-mails back and forth with "Trick Freestones" and we both felt the fuel ECU was a probable if not likely cause. So I ordered one from eBay about a week or so and am now waiting on it to arrive. I had hoped it would come last week since I had it off from work, but it will probably get here today or tomorrow. Fingers are crossed.
Rex

 

This is getting crazy now. Get a small bottle, like one that has a nipple that you can drink from. Like a water bottle or Gatorade. Fill it with fresh high octane gas. Get a vinyl or rubber hose and connect one end to the bottle nipple and one to the fuel rail, after the regulator. It should draw that gas into the injectors. If it starts your issue is from the regulator back. If not, I would say at this point you may have a faulty kill switch, bad amp or bad CPS. You said you have spark from the coil, so that is why i am saying the kill switch, lower left drivers side, has got to be causing an issue.

 

Rex,

Let's back up. I thought I asked for these, but I don't remember your answer.

1. Did you actually measure the fuel pump pressure? Did you measure 35-45 lbf/in² ?

2. Did you measure the injector signal (at each one of them) with a "Noid" light as you cranked the engine? Please see attachment for an example.

If not, you can get one at a local auto parts store. They may cost about 5 bucks. Get the one for Bosch/Lucas systems. Plug it in, crank the engine and watch it blink, indicating an injector signal. Do it for each one.

If it blinks, we have to look elsewhere. Drop your "cats" - a plugged up exhaust pipe will prevent an engine from running.

If it does not blink, we have to find out why. I think this is where we're at.

You're not going to quit on me now, are you bud?

PS So you have a backup ECU. Everyone should and you got one for domestic price.

 

1. Yes I measured pressure and I don't remember exactly what it was. i borrowed a friends tester and fitting assortment, but I remember start up pressure was what the haynes manual said-good.
2. I did not use a noid yet, I will buy one asap it is a good check, but the book always states "when running" which is why I never did it. Running does not occur.
Yes I have two ECU s now BUT, I don't know if the one I bought is good. I paid $70 and a rebuilt one is nearly $2k. From the dealership they are close to $3k. Now the car starts instantly with ether, but does not run. On my ECU the car was begining not to even start for a second with ether. PLUS- I still do not show any faults exept the obvious (door open, low brake pressure, parking brake on) I have never seen a code or number on the fascia yet.
Everything under the hood that the book says to check checks good.

 

rc,

How went the noid test?

I found something for you.

Read the first page carefully. It will help you troubleshoot the Engine Management ECU, Air Mass Meter and other sensors with ignition key ON and key OFF.

Second page is complete Engine Management schematic with wire color codes.

 

Just an update I checked out the MAF as per the static check Trick Freestones had posted and it tested good, then I tried testing the injectors with a type of "noid" (12vdc tester) but all I got was voltage to both sides constant while cranking. I don't know if the tool I borrowed would blink fast enough so I used a multimeter and it also showed steady voltage??
Also I found a place to rebuild one of my ECU units for $300 and guarantee lifetime, no one in the northern California area can test an ECU to see if it's good, nor do I know if the Voltage amplifier is good, it is hard to test output on the pins, I will try again tomorrow. Alas, still no start, but at least from all the forums I've read I can see I'm in a very large club.
Rex

 

Early on in this thread, I wrote:

Recently, Rex PM'ed me and told me the following:

Rex,

This is HUGE.

You now have eliminated a lot of maybes and now know the ECU is not sending a pulsating signal to any of the three pairs of injectors via LI2-12 (KB wire), LI2-13 (KU wire) and LI2-25 (KO wire). See my Jaɡ‧u‧ər Electrical Wiring Color Codes for an explanation of color codes.

Now could it be the ECU? Could be, but you haven't eliminated the other possibilities.

Backing up, a Test Light is not a Noid Tester.

The advantage of a Noid test here, is to verify what you seem to already know - the injectors are NOT pulsing. I like to test things in two different manners if possible - it only makes me confident with my test results

NOTE: You really shouldn't be using a test light on delicate sensors, the ECU and other Engine Management components. You should be using a digital multimeter only. The problem with using a test light is that you may inadvertently apply 12V to a 5V rated semi-conductor circuit, thus making smoke and destroying the circuit. Did I convince you?

~~~ So, I am asking you to do the following rather simple tests: ~~~

1. Using the multimeter, see if you have an AC setting. Switch it to that setting. Do not turn on the ignition switch. Disconnect the fuel injector connectors (there are two) containing the WN and KB colored wires. Choose one of those connectors. Placing the +tive (red) probe on the WN wire and the -tive (black) probe on the KB wire, now crank the engine. You are supposed to get a pulsating 12 VDC signal.

It would be neat if you can get a frequency, too, but don't worry about it if you can't.

2. Turn the ignition key to the OFF position. Turn the multimeter to the DC voltage position. Keep the test probes where they were in the previous test. What reading do you get?

3. Repeat the last test with the ignition key in the RUN position (but not cranking). What voltage do you get this time?

4. With the ignition key in the OFF position, multimeter still in the DC voltage position, measure (one at a time) the voltages from the fuel injector connector WN and KB colored wires to ground. What voltages do you get for either wire to ground?

5. Repeat the last test with the ignition key in the RUN position (but not cranking). What voltages do you get for each wire this time?

6. Now turn the ignition switch to OFF. Disconnect the battery, both terminals. Disconnect the ECU connectors. Look for the ECU pin, LI2-12 (KB wire). Keeping the aforementioned fuel injector connector disconnected and switching your multimeter to read ohms, read the resistance between the KB wire ends. It should read about 0 ohms.

7. Now keep one probe connected to either end of the KB wire and place the other probe on a good ground. Read the resistance. It should be infinite or in the Meg ohms range.

Cheers

 

Trick,
I will get the meter and try that BUT,
I got a "noid" today and just used it on all six injectors while cranking the engine and it blinks. Now I don't have another fuel injectoed car to try it out on to compare blinking vs blinking, but it certainly looks to be blinking to me. So...

 

We are watching and reading RC. I'm sure many of us wish we could be there. We know it is frustrating for you, although our hands aren't getting dirty, a lot of us are with you mentally. Keep on keeping on.