XJ40 ( XJ81 ) 1986 - 1994

Jaguar Repair Manual JHM 1130

 
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Old 03-31-2019, 08:37 PM
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Default Jaguar Repair Manual JHM 1130

I have a no start issue on my 94' XJ40.
The car started perfectly until just lately sitting out in the snow this winter.
I have been trying to fix it with the help of several on-line mechanics.
The fuel injectors just are not pulsing! and no fuel is getting from the rail to the cylinders.

I am in need of the details describing the ECM input/outputs from its 25 pin blue connector.

If anyone out there has a copy of the Jaguar Repair Manual JHM 1130 repair manual (disk) and can somehow copy the needed diagram, I would appreciate a pdf copy very much.
There may be other sources to find these input/output diagrams, I just don't know what they are.
I have a complete set of the 93 XJ6 original mechanics manuals, but they are of no help.




FE40 blue connector
 
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Old 04-01-2019, 03:24 AM
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Default ECM wiring

hello, sorry for your problems 😞 I enclose some ECM diagram


 
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Old 04-01-2019, 05:13 AM
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Old 04-01-2019, 09:25 AM
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Be aware that Jaguar issued TSBs for all sorts of issues.

The 'crappy' Blue Hella relays were a major 'pain' back-in-the-day.
We spent countless hours replacing them when I worked at the dealer.

I replaced all the faulty relays when I had my 1992 XJ40.

bob
 
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Old 04-01-2019, 10:34 AM
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Originally Posted by motorcarman View Post
Be aware that Jaguar issued TSBs for all sorts of issues.

The 'crappy' Blue Hella relays were a major 'pain' back-in-the-day.
We spent countless hours replacing them when I worked at the dealer.

I replaced all the faulty relays when I had my 1992 XJ40.

bob

Forgot about those damn blue relays, replaced all of mine with sealed units back when I got the car!

The one in the group on the firewall that switches the oxygen sensor heater can shut off the fuel if it's faulty or has a bad connection and of course the fuse boxes are very problematic on the late cars too.

Larry
 
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Old 04-01-2019, 09:16 PM
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Hi wemertz,

The pinouts for the ECM are in the Electrical Guide, which you can download at this link, courtesy of our member Gus:

Jaguar XJ40 Electrical Guide 1993 1994

Regarding your no-start, the most common cause in Jaguars is low battery voltage while cranking. If the voltage falls much below 11V while cranking, the ECM will not trigger the ignition to fire.

Can you hear the fuel pump run briefly to prime the fuel rail when you turn the key to position II (ON) without cranking the engine? If not, I can post a diagnostic procedure that will help you determine whether the problem is the pump or its electrical circuit.

Please keep us informed.

Cheers,

Don
 
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Old 04-03-2019, 12:30 PM
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Don,
I was wondering if anyone (including Gus of course) out there has a copy of the foldout mentioned on Fig 30.
That would tell me what I am looking for in regard to the output voltage to the fuel injector.
Right now, while cranking, I am only getting 5 volts to the injectors.
Maybe that is enough for the VCM to send a ground signal to the injector, I just don't know.

So, a copy of that foldout would be very helpful and much appreciated.

Thanks,

Wayne
 
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Old 04-03-2019, 01:03 PM
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Wayne - I think you've discovered a missing page!

(at least I couldn't find it!)

However I believe you need 12v at the injectors.

Maybe of no use, but, one thing I read said that IF the ecu sees a wide open throttle signal from the TPS during cranking, it prevents the injectors from firing apparently to prevent engine flooding ...

Larry
 

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Old 04-03-2019, 06:14 PM
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Originally Posted by wemertz View Post
Don,
I was wondering if anyone (including Gus of course) out there has a copy of the foldout mentioned on Fig 30.
That would tell me what I am looking for in regard to the output voltage to the fuel injector.
Right now, while cranking, I am only getting 5 volts to the injectors.
Maybe that is enough for the VCM to send a ground signal to the injector, I just don't know.
Hi Wayne,

Sorry for the delay in responding, but we just moved and I had to track down my printed copy of the 1993 Electrical Guide. There is indeed an additional foldout page for Figure 30 that was not scanned into the pdf version of the guide we've all used for years.

First of all, the Injector Supply is shown at the bottom of the Figure 30 Data page at Output code FE40-12 and FE40-17, and it is battery voltage, so 5 volts would definitely be low. However, since the ground signal is pulsed via the ECM, to measure your injector supply you need to measure between one of the Pink wires with Blue tracer lines (color code KU) and a good ground, such as one of the intake manifold studs. If you measure across the two terminals in an injector electrical connector, the ground via the ECM is pulse-width modulated (PWM), so you're measuring a type of Alternating Current rather than Direct Current, so your reading will be off.

The Injector Drive signal is also shown at the bottom of the Figure 30 Data page as Output code FE40-13; this is the PWM ground via the ECM, and the spec is "Pulsed Signal (2.6 MS IDLE)." I assume this means the pulse width is 2.6 milliseconds at idle. The foldout page that is missing from the pdf scan shows the redundant Injector Drive Output from the ECM, FE40-25, with the same spec as FE40-13.

Once I get the scanner back up and running, I'll try to remember to scan the foldout and add it to the pdf and post it here at JF. Thanks for catching that it was missing from the pdf, Wayne. You have a sharp eye!

Cheers,

Don
 

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Old 04-04-2019, 10:25 PM
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Don,I was not able to get the Jag started, so I had to push it out into the lot.I have been having problems with my other cars, so I had to get at them.I will try to get back to it, with luck, in a week or so.Thanks again for your help,Wayne
 
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