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equiprx,
In one of my manuals, it has one marked (cat only) Li123, but I'm pretty sure they are referring to a relay not a fuse. It shows it located mid-engine in the engine bay. My car doesn't have one, so I guess it doesn't apply. My owners manual lists a 5 amp fuse in the right side of my boot for a heated oxygen sensor. I only found one 5 amp fuse back there and it tested good.
You have one problem to solve: Why isn't the relay apparently able to energise the fuel pump? Don't bother trying to start the car any other way or look for any other issues.
There are a few questions that need to be sorted: .
You say that you've looked through the 93 Drivers handbook and the detail of each fusebox and relay location, and you can't find reference to a fuel pump relay fuse, a fuel injection relay or a fuel injection relay fuse? In my documentation pack, the fuses and relays are detailed in the Vehicle Care booklet (105 pages). I don't know if you have that in the 93 documentation? However, just in case it's of any help, the 94 Vehicle Care booklet refers to the following:
- The fuel injection main relay is in the inner rear wheelarch and is silver / red in colour with a red base
- The fuel injection relay fuse is in the right hand fuse box (in front of the knee bolster) is Fuse 20 and is 20amp
- The fuel pump relay fuse is in the right hand rear fuse box (by the aerial) and is Fuse 12 and is 20 amp
Of course, it may all be completely different on a 93 car, but I'm not sure why that would be, so I'm slightly confused by your summary of the 93 Documentation? .
If you look at the wiring diagrams, you'll see that the live feed to the fuel pump relay has a energiser / interrupt control that is triggered from the ecu from L192-7 to post 85 of the relay. The 93 electrical diagram also says that when that ecu output is "active", it is "grounded. And when it is "inactive", it is 12v. Also, if you read the fuel system description in the workshop manual, it SEEMS to imply that the ecu doesn't start the 2 second cycle when the ignition is turned on, instead it stops the relay after 2 seconds. So I don't know if the ecu output is "active to turn off the relay, or "active" to allow it to run. Perhaps Greg can advise?
If you can work out whether the L192-7 output is 12v moving to ground after 2 seconds, or ground moving to 12v after 2 seconds, then you can pin down the problem. Because as long as it changes after 2 seconds, the problem seems to lie with the fuse pump relay or the relay holder. As you've bridged the relay from live feed to output to pump and the pump runs, I don't think it's the fuse at fault because presumable that's on the live feed to terminal 30? (I might be wrong in that assumption?)
As you'll know from the Jaguar parts website, the fuel pump relay is part number AGU1068. I believe there is at least one other AGU1068 in the car, on a bracket in front of one of the knee bolsters. If you do a search for the part number on the Jaguar parts website, you'll find where it is. If the ecu output and relay holder seem to be sound, you could try swapping this other AGU1068 relay and see if the pump then runs.
Paul,
The fuses next to my aerial are a 3 amp, 5 amp. and a 10 amp., all tested good. We are not getting power to the fuel pump relay. The fuel pump relay tested good. If we can get power to the fuel pump relay so it will then activate the fuel pump, I think the car will start.
You said that you ARE getting a live feed to the relay holder as you bridged terminals 30 and 87 and the pump ran. Therefore, the problem doesn't seem to be on a pure live feed, but on a relay trigger feed. So as I mentioned, you need to verify the output trigger signal from the ecu and whether it is going to the relay holder.
I just ordered a replacement ECM with the same DAC number. When it arrives I will plug it in and if the car starts, problem solved and I have my car again. If not, I'm back where I started only I will have a spare ECM.
We have gotten to a point that we know the fuel pump relay is not getting voltage, but nobody seems to know why. You said: "You need to verify the output trigger signal from the ecu." So, tell me how do I do that?
I think the Blue Relays that Paul (ptjs) was referring to may have been these in this Pic as they are well known for causing No Start Problems because the Blades are so thin that sometimes they don't make proper Contact in their Holders, so Swap them about and Jiggle them and who knows the Car might just Start and if it does then Swap them out for some Hella Relays that have Thicker Blades
You will find these Relays inside the Knee Panel Fuse Box Hidden away just above the Fuses
OB, I just went out and took them out, sprayed contact cleaner in the contacts, switched them and it didn't start. I also took out a spark plug to make sure and it was dry.
I stongly suggest that you should to consult the wiring diagram and from it find out where the pump relay trigger circuit gets its 12v feed from. Then work back along that circuit; from the relay, to find out where/why the 12v is not arriving. It is clear from your tests that this is the fault, you now need to find the cause.
Just to make sure you haven't got an 'Odd Ball' registered Car
Can you Confirm that your Engine has got a Coil and a Distributor
Or does your Car have a Separate Coil for each Spark Plug, because if so then you would have a 'Crank Position Sensor' which is almost always the cause of a no start problem and is easily fixed
If you give Paul (ptjs) the Vin Number, he will be able to tell you what you need to know
Greg in France,
As I have said from the beginning, I am not a Jaguar mechanic or a electronic engineer. I've only been working on this car for the last couple of months. Greg of France and Paul have both suggested that I go figure this out. If I could have done that, it would have already been done. Let's just hope the replacement ECM will fix my problem, or else my car will be of no use.
OK, I've done a shed-load of reading up and googling on this today and the following MAY be of help. Of course, I may well have got something wrong, in which case I apologise!
- For some reason, a 93 4 litre doesn't seem to have a fuse for the fuel pump relay, or for the Fuel Injection / EMS relay. I don't know why, but they just don't seem to be detailed anywhere.
- There IS a Fuel Injection / EMS relay on a 93. This controls the power feed to the ECU / ECM. All the correspondence seems to indicate that this is mounted alone on the right-hand A-Post. Not sure if that means inside the car, but I would guess so. It's silver with a red stripe and it's mounted on a red relay base.
- The Fuel Injection / EMS relay works in the following way: Battery voltage is coming in on terminal 30 via a Brown wire. When the ignition is turned on, the relay should be energised by voltage coming in on terminal 86 via a White and Pink wire. The relay is then energised and provides power to the ECU / ECM via terminal 87 on a White and Brown wire.
- So, the first test that you should do is to check that you can see voltage coming in on terminal 30. Then turn on the ignition and you should be able to read voltage coming in on terminal 86. Then you should be able to see output voltage to the ECM / ECU on terminal 87. If that doesn't check out, then stop and check the relay and relay holder.
- Once the ECM / ECU is energised, it can then provide control to the Fuel Pump relay.
- The Fuel Pump relay takes battery power on terminal 30 via a Brown wire. When the ignition is turned on, it should be energised voltage coming in from the ECM / ECU on terminal 85 via a Brown and Pink wire. (I think that's right). But remember it will only be energised for 2 seconds. Although when the engine is cranking, it should be re-energised again.
- So, if the first test is successful, the next test is to check that the Fuel pump relay is receiving a control current on terminal 85 for 2 seconds when the ignition is turned on. (We already know that it is receiving battery voltage on terminal 30 from your previous test.)
When doing all of the tests, try and back probe the relay holder to check the current is getting to the relay holder. But you might also want to first remove the relays and do a continuity check on each terminal of the holder to confirm that the relay holder has integrity on each of the terminals.
If you want, there are further tests we can do on the input and output circuits of the ECM / ECU, but do the above tests first as that will help to pinpoint down the issue.
Hope that helps. If anyone thinks that I am misreading the electrical circuits, do please shout. I won't be in the slightest offended!
Paul
PS I've only just realised from your post of 23/11 that you removed the ECM / ECU! Has the car ever started since you re-installed it? This feels really important!
Thank you Paul. I went and searched the whole car and I did not find a silver/red stripe relay on a red connector. But, I did find a red connector with a purple relay on the passenger side of the car. I figure maybe someone put this on on there either by mistake or was just using it as a replacement. So, being I have nothing to loose, I took it out and tested it. I could NOT get it to work no matter what terminals I hooked up my wires to. So, it appears this relay might be bad. If it has anything do with the problem I am faced with is yet to be determined. This relay has Jaguar DAC 7687 on it. Is there one on my car that I can take to replace this one to see if my car will start? Yes, my car started several times before it quit.
Were you able to see if that fuse had 12v power?
Did you check continuity at the terminals, NOT just the ends of the fuse?
Here is a proper Fuel Pump relay if you want it.
Sorry for the blurry pic.
The Bosch PN is 0332016112.
I don't ever trust a visual on fuses, I test them with a volt meter. The only metal relay I have found in my car was the one for the fuel pump and that one tested good. If you read my post before this one , you will see what I have found. Right now I am recharging my battery again. If I can use another relay that is of no need, I will try it to see if my car will start. We can only hope.
I'd suggest you don't start swapping around unknown relays. The fuel pump and other metal case relays are heavier duty than standard plastic relays. I THINK that DAC7687 is a transmission warning relay. Exactly where did you find this purple relay? Perhaps post a photo of the location.
You really need to be sure that you have found the Fuel Injection / EMS relay before you go any further. I know you have all this info but here are the location pics and details of all the 93 relays. From this, you should .be able to find the correct relay.
11-27-2022, 02:02 PM
