I have no spark from coil HT lead to distributer (when tested on engine as an earth). This was after a head gasket replacement and rebuild.

Wires broke on the 3 white snap connector from LT coil, so I had to reconnect them. White wire in middle to coil +ve now OK (tested 12v), and I connected ECU Blue/White wire to Black/White wire to coil -ve (tested earth ok). Did not find any wire from coil -ve for third connection which had a White / Grey / Blue wire from tachometer but I did notice in the wiring loom a black/white wire out mid way down alongside rocker cover which I had connected to coil -ve as it was black/white. Should this had been connected to 3 snap connecter to tachometer. When cranking car I heard a loud bang like a weak fuel bang much to my alarm. Could I have damaged the coil though a bad HT lead not allowing the spark to earth.

Further testing revealed I was not getting a spark from coil HT lead to engine block. When I put a meter across coil +ve and -ve the meter dropped to 0.35v, which suggested a coil problem. Continuous test done on coil was OK. So I have ordered a second coil to substitute the original which I am awaiting. When I put did a continuous test on coils HT lead with a meter I did not get anything so possibly I have a bad HT lead.

Can anyone offer me advice on A) the wiring of the 3 snap connector(Apart from +ve ignition wire and -ve wire from ECU to coil.) from anyone who has this model B) Whether I should invest in some new HT leads as well when I fit the replacement coil.

 

I'm not entirely clear on what you've posted, sorry.

Do you have Lucas CEI or Lucas OPUS ignition? I ask because some early Ser IIIs apparently had Lucas OPUS.

If Lucas CEI the coil "+" post should have all solid white wires. The "-" post should have white/black wires and the white/blue/slate. If you have OPUS I'm not sure what the wiring should be.



Here's a diag tree for the CEI system.

The test assumes a fully charged battery

1) Measure voltage at coil "+" terminal with key "on". It should be within
one volt of battery voltage. If not suspect a problem with the wiring to the
ignition switch, or the switch itself.

2) Measure voltage at the coil "-" terminal. Result should be the same as at
the "+" terminal. If Ok, go to step 3. If not....
Disconnect the wire from the amplifier from the "-" post of the coil and
measure voltage again. Less than 2 volts means the coil is faulty. More than
2 volts means the amplifier is faulty.

3) Disconnect distributor pickup coil from the amplifier (this is the
harness from the distributor that plugs into the amp). Measure resistance
across the terminals. It should be 2.2k to 4.8k ohms. If Ok, go to step 4.
If not, replace the pickup.

4) Reconnect the pickup to the amplifier. Measure voltage at coil "-" post
while cranking engine. The voltage should drop. If OK, go to step 5. If
not, the amplifier is faulty.

5) Check distributor cap and wires, distributor rotor arm, spark plugs, coil
wire




Hope this helps in some way

Cheers
DD

 

Thanks for the info, Doug

Think my S3 has a Constant Energy system Lucas 45DM6 distributor. The LT wires are white on coil +ve and black n white on coil -ve. I can verify have just over 12v (something like 12.8v) on +ve coil terminal +earth on engine, but only 0.35v between coils -ve and -ve terminals. When I get my replacement coil I will take the steps you advise.

Cheers
Ken

 

Doug,
I have followed the steps you advised . I am still in despair of a spark, any furtheradvice would be very welcome.
To clarifymy XJ6 s3 1979 4.2 Auto car has a standard system is constant energy CE1ignition system on it with new replacement Lucas coil DLB198, new HT leads,Lucas distributor 45DM6 and pickup, standard amp AB14 (with a GM high energyHEI module, one noise reduction switching capacitor, one over charge protectionzenior diode)
Battery is fully charged at 12.5 v, -ve earth (ground). Previousrecent work done to car. I had replaced the head gasket on car. Before this carwas running with a spark but over heating, some wires broke on assembly on thewhite 3 prong connector near coil and had to be fixed. Early i had flushed water to clear head waterways which could have soaked ignition amp or distributor.
General wiring
In 3 prong white plastic connector next to coil is
One harness blue/white wire (assumed from ECU) reconnectedto / black/white to coil –ve,
One harness white live wire (with ignition switched on)recoonected to / white wire to coil +ve,
One tach blue/white/slate / (think goes to coil –ve or theharness wire mentioned below)
Have one harness short black / white wire with a spade(think goes to coil-ve or tach wire)
One black/white wire from amp (output pulse grounding) tocoil –ve
One white wire from amp (output pulse grounding) to coil +ve
Ground of amp casing mounting bolt
Pick up 2 black wires to amp (input pulse) connector twospades.
Short HT lead from coil to distributor centre to rotor to 6HT plug leads to ground through plug gaps to engine.
I don’t think it is important that the distributor or coilcasing needs to ground, but i stand to be corrected
Doug: Do you still have a diagram tree. I could not find itin your first reply/assistance.
When I disconnect the coil HT lead to be ¼ away from engineground and cranked car, I got no series of sparks but except to say I did seeone spark at the end of cranking on some occasions suggesting something workedbut not continuously, perhaps the amp?
Testing steps you suggested
1) I bought a new DLB198 1.6 ohms coil and new HT leads andfitted them to the car
Measured battery at 12.5V, COIL + terminal to ground onengine measured 12.18V so OK
2) COIL – terminal to ground on engine measured 12.18V and as Coil’s resistanceis very low at 1.5 ohms this is ok

Thought I would carry out this disconnect amp’s –ve feed tocoil test despite the ok results from test 2 being OK anyway
With ignition on I got oddly no drop or rise in voltage ondisconnection of amp –ve wire to coil –ve but the same 12.18 v I hadbefore. (note I did not crank enginewhen taking this measure or take any other wire off coil). You say morethan 2 v then I need to investigate the amplifier
Note also at this stage i thought the feed to the amp i.ethe pick up coil may also need investigation to a sufficient air gap and theamp may not be producing any grounding pulse to amp to allow a spark to becreated from coil because or this factor. (see later investigation of amp andpick up )
3) Got a measure of 3.6k ohms across pickup wire connectorwithin Jaguar range so think the pick up is ok
I decided to take the distributor and amp off car toinvestigate them further.
Believe because any standard coil has to be able to be givensufficient time to charge up between sparks and having more 6 or more cylinderswill make this harder Jaguar elected to use a constant energy system in placeof the OPUS original on the xj6 / xj12 s3 and used a GM High energy switchingchip component in a amplifier to achieve this in between the 6 pick up pulsesper engine cycle rather than use a conventional non amplifier arrangement soelected for a small pick up voltage out of 1.5 v rather than 12v that needed tobe stepped up to 12v by the amp.
Amp
I looked inside amp, found 1 capacitor internally connectedto C spade of GM high energy HEI module, 1 zenior diode internally connected toG (ground) spade of GM HEI, two wires from HEI out of amp, one b/w – and one wwire –ve from these two spades.
Note my car’s amp does not have the v shaped white rubbercontaining a 6.6 resistor to ECU EFI (white/gray wire in it or a 10 ohmresistor to tach, so car may be set up in UK different to USA.
I found a slight bit of white powder on amp casing nearcapacitor that could be the aluminium casing oxide. I did not think this was GM HE1’s poisonessand expensive heat sink ceramic (beryllia powder) but I was careful to clean itaway just in case. There was no obvious sign of anything blown insde amp. Internal connections checked for continuous,ok
Distributor
Cleaned distributor 6 pronged iron wheel of rust and decidedto reset air gap using a 15 thou steel feeler gauge.
On manual rotation of rotor i got very small voltage acrosspick up wires of around -/+ 0.06 volts (when meter set on 20v range) should i try to reset air gap smaller to getmore voltage from pick up when i rotate rotor. (think it should be 1.5 voltsnot 0.06 volts)
Wiring
The two black wires from pick up to amp look in goodcondition and tested continuous. Two ampwires to GM HE1 test continuous.
Further testing
When I further connected pick up wires out of car to amp Imeasured no voltage from the two amp wires to coil. (I was expecting say a 12v grounding pulse tocoil when the distributor rotor is rotated again).
Jaguar guide says if get zero volts (Doug you advised lessthan 2v) it should be a faulty coil (my coil is new) if get 12v (Doug you advisedgreater than 2v) it is a faulty amp.
My test of amp output pulse could have been going wrongbecause i had not earthed the amp out of the car. Think I should ensure the amp is fullyearthed first by running an extra test wire from amp to battery –ve whilst as Iam told the GM HE1 in US has a 5th connection which runs it’s –veearth through one of its mounting points inside the amp and the amp thereforeshould be earthed.
Tried manually tapping the live feed wire from battery +veonto the coil +ve terminal to see if i got a spark out of car, but oddly I gotno spark. This however could have been because i was using a poor or no earthpoint to do this test properly.

4) Early on car when I connected a test bulb across (inparallel) the –ve coil and ground with ignition on, 12v bulb lighted upbrightly but it did not blink on cranking engine which I think suggested afaulty amplifier or pick wiring or air gap




5) If it is the amp this is big bucks and hard to find inthe UK. I may be able to get a breakerto help me I have looked to see if a replacement GM HE1 instead ratherthan try to locate a replacement amp (GM No 10482820 or 19180771). Looked onebay-uk to see if is available from a uk supplier. It does not look like it. It has to be imported from US with a largerpostage fee and I gather a customs clearance and it’s a hit and miss affairwhether it will work properly in the amp even when it is fitted.
I am told the GM HE1 can be replaced with a part numbersfrom USA suppliers AC Delco number D1906, or Napa number TP45 or Accel number35361 or Standard Motor Products LX301
Do you have any extra suggestions or pointers on what Ishould do to get a spark.
Cheers in ernest
KenXJ
London UK

 

Can you post a picture of this?





Some of what you're describing doesn't sound familiar to me. Perhaps because yours is such an early car?

Any solid white wires go to the coil "+" post. Anything else goes to the coil "-" post. At least on every CEI car I've worked on. I think that's what you've just described.

A plastic connector is foreign to me as is a blue/white wire. Do you have any idea where the blue/white wire terminates? Starter relay, perhaps? Just wondering. The 3.4 cars (with breaker points ignition) used a white/blue wire from the starter relay to bypass a coil ballast resistor for starting.





Sorry. The "tree" mentioned/shown above is simply text from the service manual. It originally looked like a troubleshooting "tree"






Or a problem with the ignition switch

Have you tried using a jumper wire to provide 12v+ directly to the coil "+" post?




I agree






Not rigning any bells....but my memory is foggy. Been a number of years since I opened up an AB14





I'll have to digest some of this





The "2v" is right out of the Jaguar ROM <shrug>


My test of amp output pulse could have been going wrongbecause i had not earthed the amp out of the car. Think I should ensure the amp is fullyearthed first by running an extra test wire from amp to battery –ve whilst as Iam told the GM HE1 in US has a 5th connection which runs it’s –veearth through one of its mounting points inside the amp and the amp thereforeshould be earthed.
Tried manually tapping the live feed wire from battery +veonto the coil +ve terminal to see if i got a spark out of car, but oddly I gotno spark. This however could have been because i was using a poor or no earthpoint to do this test properly.

4) Early on car when I connected a test bulb across (inparallel) the –ve coil and ground with ignition on, 12v bulb lighted upbrightly but it did not blink on cranking engine which I think suggested afaulty amplifier or pick wiring or air gap




5) If it is the amp this is big bucks and hard to find inthe UK. I may be able to get a breakerto help me I have looked to see if a replacement GM HE1 instead ratherthan try to locate a replacement amp (GM No 10482820 or 19180771). Looked onebay-uk to see if is available from a uk supplier. It does not look like it. It has to be imported from US with a largerpostage fee and I gather a customs clearance and it’s a hit and miss affairwhether it will work properly in the amp even when it is fitted. [/quote]



Hit and miss, how? That's definitely what was used....so it should work properly.

Or are you saying it's hit and miss that replacing it will solve your problem?



Right. Many prefer sticking with the genuine Delco (D1906)/GM (10482820 or 19180771) versions, though






I'll try to come back later on this after some re-reading and mulling.

Cheers
DD

 

Thanks for the quick reply Doug

I have not put dist, amp, coil back on car. Have not got a photo yet of 3 spade connecter but to describe it. it is a creamy small plastic about 1 1/2 long and thin and has two parts of 1 inch or less in width that push together the wires push in one part from the harness to the part with wires from the coil. We agree white wire goes to +ve terminal of coil and all other wires go to -ve terminal of coil. For some reason the wires from harness are blue/white (from ECU no 1 terminal in boot I think) and a blue/white/slate (believed to be from tach) and the white wire. The coils 2 wires -ve into the connector are black/white and the white +ve wire.

As the car was previously running before I worked on the head gasket I think my problem lies with the wiring as this 3 spade connector broke and was messed around with. But when I first cranked the car on head assembly I heard a loud bang like weak fuel. The engine was put together ok mechanically and spins OK. After which I started to investigate why I had no spark at the COIL HT lead to engine ground. It is possible something shorted due water falling in the electrics on flushing out waterways on the RH side inlet manifold side (UK) like the amp or distributor.
2) Have not tried a jumper lead to coil +ve yet but I will try this. Note when I tested terminals on coil they shown 12.18 volts but perhaps I need to run a jumper test lead from the battery just to be sure.
4) When took -ve wire of amp off coil -ve terminal I got 12.18 volts as when it was connected. No drop under 2 volts or more than 2 volts. May have to repeat this test to see what is happening.
5) I agree if it is the AMP GM HEI it could be replaced but I have not yet ascertained it is the amp for sure. May try to get a substitute amp from a breakers as my next step.
Thanks
Ken XJ