Wiring diagram needed

[Ireland]

A friend of mine with a '96 Chimera is having trouble getting to the bottom of an electrical fault that's resulting in no power getting to the fuel pump.

Is there an on-line wiring diagram available anywhere?

If so, can someone post a link.


Thanks in advance.

Irl

[Ireland]

[Ribol]

Don't have a wiring diagram but just a thought, have you checked the inertia switch before you get too involved?

[spend]

Theres one of mine at http://tvr3.dspen.com/Wiring_Diags/lucasecu.png (a pdf as well). Not sure if it is complete, but all the fuel stuff is IIRC.

Dave

[Ireland]

Ribol said:

Don't have a wiring diagram but just a thought, have you checked the inertia switch before you get too involved?

Yes, tried it but no joy.

Also tried the relays.

And rang Carl Baker but still stuck.

He's got a mate who's an auto-electrician coming to help him at the weekend so that's why we're looking for the diagram.

But thanks for the suggestion .....

[Ireland]

spend said:

Theres one of mine at http://tvr3.dspen.com/Wiring_Diags/lucasecu.png (a pdf as well). Not sure if it is complete, but all the fuel stuff is IIRC.

Dave

Cheers.

I'd posted my last post before I saw this one.

I'll text him now and let him know it's there.

Thanks for that.

[Ribol]

Ireland said:

Ribol said:

Don't have a wiring diagram but just a thought, have you checked the inertia switch before you get too involved?

Yes, tried it but no joy.

Also tried the relays.

Have you checked if the fuel pump relay is being energised? If it isn't then you may be looking at immobilser/alarm problems.

[GreenV8S]

Don't have a picture, but I can give you a rough description.

There are two circuits through the fuel pump relay. The control circuit has a fused 12v supply which goes through the relay coil and is earthed via the ECU. The power circuit has a permanent live fused 12v supply, switched through the relay, out via the inertia cut-off to the fuel pump. The other side of the fuel pump is earthed. If you have an immobiliser it is usually wired into the ignition switched supply which takes out the power to the control circuit and also stops the ECU from being powered up.

It's fairly simple to follow the power through and find the fault once you know how it's supposed to work. Unfortunately, figuring out how it's supposed to work is tricky once it's broken. Hopefully the above description gives you a rough idea. Start from the fuel pump relay and work back through both circuits to see which one's broken.

[Ireland]

Thanks for that folks.

I've just sent a text to the owner of the car so he'll probably be along here later to ask more questions, or to thank you all if it works for him.

[Corso Marche]

Thanks guys, it's actually my car has the problem at the moment. '95 Chimaera 4.0 de-cat.

The car started and drove out of the garage one day, but when I went to re-start it the fuel pump began to prime but then cut-out. Now there is no power at the pump at any stage.
We originally ruled out the immobiliser system because when its deactivated you can still crank the engine over as usual and if there is any fuel in the fuel system it will fire on a few cylinders and then die once that fuel is exhausted.
Spoke with Carl Baker and he was extremely helpful and friendly and pointed me to a few areas where he had seen similar problems in the past.
The Bosch relay on the black connector will click as normal when the immobiliser is de-activated, but the one on the blue connector (which is triggered by the one on the black connector) will not. Seeing as both relays are the same I swapped them over but nothing changes, all I established was that both relays are actually functioning.
Also checked the inertia cut-off switch and its not this either.
So now its looking like we'll have to delve into the looms.
The only fuses I could find were the ones above the battery box, is this correct or are there more hidden somewhere else on the car ?

I think this could be the start of much head-scratching !!

[spend]

The blue connector houses the fuel relay, the black housing is the main relay normally. Any twin make break relay can be used for testing (really need a diode but they should work ok without, just dont make any big sparks or leave to drain the battery?)

Dave

[Cider Andy]

Neither relay is triggered by the other. The fuel pump relay should have an ignition-switched live on pin 86; its coil is controlled by the ECU grounding pin 85.

Check for +12V at pin 86 on the fuel pump relay. If present, check the connector to the ECU for corroded or dirty contacts.

[Corso Marche]

Thanks guys, I'll check these and report back.

[Ribol]

Corso Marche said:

We originally ruled out the immobiliser system because when its deactivated you can still crank the engine over as usual and if there is any fuel in the fuel system it will fire on a few cylinders and then die once that fuel is exhausted.

As we are past the obvious ones, some old alarms have one cut built in and a second cut via an external relay controlled by the alarm. This system was used on early Foxguard alarms as well as others.
In this situation the alarm might allow the car to crank(cut one), also connect cut 2 but if the external relay making the connection is dead it could cause a problem.

Just a thought, good luck.

[Corso Marche]

Thanks Ribol, after speaking to Carl Baker he thinks perhaps the alarm/immobiliser system in my car was changed before. There is a Laserline system fitted to it but he reckons it would have left the factory with a Foxguard system.

[SMB]

Corso Marche said:

Thanks Ribol, after speaking to Carl Baker he thinks perhaps the alarm/immobiliser system in my car was changed before. There is a Laserline system fitted to it but he reckons it would have left the factory with a Foxguard system.

it should have had a foxguard as std back in 95. Mines the same vintage and i can say that the bosch relays for the ecu and fuel pump fail fairly regulary. Don't swap them with each other, just swap them out for new, relatively cheap and always good to have some spares. I had exactly the same issue once, car started, reversed out of garage, and died on the drive, no fuel pump power, after some debate, swapped both relays, worked fine since.

[spend]

I have a laserline, but the wiring diagram is just all yellow wires It works if you bypass the immob circuits tho (I think 1 needed leaving live to the alarm unit).

Dave

[Corso Marche]

Well guess what ? Both old relays worked when in the black connector but neither would work when in the blue connector. I ordered 2 new ones regardless last Tuesday and they arrived today (things take a little longer across the Irish Sea I'm afraid) as I was going to replace these with new ones anyway when putting the car back together after hearing they gave so much trouble. Preventative maintenance for the future I thought. Went home tonight, into the garage where the Chimaera was still sitting on axle stands, fitted both new relays, turned on the ignition, deactivated the immobiliser, and BINGO, in comes the fuel pump. Dropped the car to the floor and it started up on the first turn of the key.

Now, if it would only stop raining. . .

Thanks for all the info guys, I'll be sure and keep it for future reference. Greatly appreciated.

Oh, and big thanks to Carl Baker for being such a helpful and friendly bloke. Respect & thanks due.

[Ireland]

Another positive result.

I'll clear the garage ......

Time for another thread about how to get the stud out of the diff, methinks.