What diagnostic tool should I get to read the codes on the ECU of my 1987 XJ6?

Thanks for the information.

Neal Lewis

 

A small hammer for the relays.

 

Since this is a fine British car, just how many kilo Newtons should be judiciously applied to each relay? ;-)

 

I'm a kid in the '70's working at an MG/ Triumph dealer, and the bloke who was the shop foreman has me pushing the horn button on a Spitfire while he is looking for the problem. "Get me a tap stick" he says, and I climb out of the car and say "Huh?"

"A tap stick, I need a bloody TAP STICK !" So I run to my toolbox, grab a little ball peen hammer, and he whacks the Lucas horn back to life while I resume my button-pushing assignment.

The only factory diagnostic tools for a 1987 XJ6 were a cruise control system tester (awesome), a climate control system tester (useless), and a Lucas Fuel Injection System Epitester. That was a comical endeavor, I never found a single problem with that unit that I couldn't have found with multimeter...or the tap stick.

I think there was also a Lucas Electronic Ignition tester, but I never saw one. Fault codes didn't exist back then. Just tow trucks.

If you have a Home Market 1987 XJ40, that will store six codes which can be viewed on the VCM screen by pushing the button. Kind of like playing Pong, it doesn't seem that long ago but things were not very state of the art.

Of course those first digital dashboards had their problems too, the gauges would blank out. Try smacking it in the top left corner, it will usually light up if only for a few seconds. Huh, not working? Wait, I'll go get you a tap stick.

 

Loved the story. Wonderful.

The car is an XJ6 not the XJ40. From what I understand, the control computer should have diagnostic capabilities and I should be able to hook an analyzer to it. It is in the trunk.

I know my 1987 AMC Eagle has a computer that I can plug an analyzer into. The level of the other electronics on the Jaguar lead me to believe that is possible with it too.

If I am wrong, OK.

Thanks for your help,

Neal

 

That's what the Epitester was, it connected in series at the ECU. It tested inputs
(coolant and air temp sensor readings, cranking signal, air flow meter, full load switch) and you could use it to actuate each fuel injector to perform flow tests. Basically tested components in the system and thereby test the ECU via elimination. It gave you analog voltage and resistance readings, but there were no fault codes of any sort, or self-test of the ECU.

Is all of this as a result of a problem you are having with your car?

 

Yes.

The car will not run. When it did run, it ran rich and very rough. I hate to replace sensors ***** nilly without trying to diagnose them first.

I hope to have the official shop manual in a week or two (it is on order and should arrive in that time frame). That should help me in the diagnostic process and enable me to quit bothering you guys quite as much.

There are a multitude of small problems, electronic and otherwise that need to be taken care of on the car. I would prefer to correctly address the right ones and make as quick a progress as possible. Plus which, it will save resources in the long run.

I am willing to buy an Epitester (or the modern equivalent) if it helps me do that.

Thanks,

Neal Lewis

 

I thought you ordered that book like three weeks ago. What, they're still cutting down the trees? I have one if you need it.

 

Here are some special tools and modern equivalents that might prove useful:

 

Preliminary check on your vehicle from my experience would be battery voltage under load test, connections including chassis and engine ground straps, resistance measured through fuel injection coolant temperature sensor (or substitution), fuel pressure test.

The fuel pressure regulators have an occasional but nasty habit of failing after 100K, your engine may be overfueling and eventually flooding because the regulator is causing fuel injector pressures to well exceed 40PSI.

 

Were you getting large plumes of think black smoke out of the exhaust before it gave up the ghost?

 

I will start to do the testing you recommended.

As to the manual . . . I had to order from a different source. The first order (both placed on Amazon.com) was from a fellow who never delivered and has no more store on Amazon. I am in the process of trying to get my money back on that transaction. I think it should go well since it appears Amazon shut him down and I used a credit card.

The next attempt to get a manual was done just a couple of days ago. Hopefully that will show up in a couple of weeks (via media mail).

Thanks again for the input. I will try to keep you posted with how things are going (on the testing procedure).

Best wishes,

Neal Lewis

 

No thick clouds of black smoke, but a very strong smell of gasoline.

Neal

 

One quick test, try pulling the small vacuum hose off the fuel pressure regulator and see if there is fuel in it. See if the regulator holds vacuum. Just don't get a mouthful of gas, that's one of the ways to test to see if it has failed. The other requires a fuel pressure gauge.