ECU replaced in my VS Commodore & then the fuel pump went
ECU was replaced week and half ago then I got the car back drove it for 2 days then the car just stopped again what I thought was again the ECU the mechanic reckons the fuel pump had to be replaced and that the fuel pump blew the fuse in the ECU. Am I getting taken for a ride or is the ECU and fuel pump linked in some way?
Ta
There are no fuses as such in the ECU.There are fuses in the circuits that supply power to the ECU though.The ECU commands the fuel pump on and off so they are,in a way,linked.The ECU should power up the fuel pump for 2 seconds when the ignition key is turned to the on position,then the ECU should shut it off again,and the fuel pump should run constantly if the engine is running.Theres a Green/white that supplies power to the fuel pump relay to turn the pump on and off,this wire goes from the ECU connector plug A6 (on the middle pink ECU connector),to the fuel pump relay,which is located under the bonnet near the fuses etc.Id check the connections and wiring from the ECU to the fuel pump relay,but firstly Id change the fuel pump relay itself,swap it with one the same like the LP check relay next to the fuel pump relay and then see what happens.
Last edited by Brett_jjj; 16-02-2011 at 11:51 AM.
Sounds like your mechanic is fault diagnosing by substitution, always ask for your old parts returned to you, you should not be paying for his parts if he is substituting to eliminate a fault.
Fuel pump is fused and relay controlled by the ECU outside of the ECU.
okay thanks. So is what you are saying is that it could have been the fuel pump or the fuses in the circuit in the start rather than the ECU.
How it originally occurred was that we were driving and the car just stopped. Lights on dash were working but car wouldn't turn over and the remote keys wouldn't lock car. NRMA said it was more than likely the ECU so auto electrician replaced the ECU cost me $200 with labour. Then got the car back drove it for 2 days went to start it and it ran very rough then it just stopped same thing no immobiliser light flashing or the remote keys wouldn't lock the car so I assumed it was the ECU again but auto electrician has replaced the fuel pump. I pick up the car this arvo so am just wanting to have some knowledge or info...I hate not knowing
Ta Sharon
The remotes on the keys dont even communicate with the ECU,they communicate with the body computer or BCM (Body Control Module),so it wont be the ECU thats causing the locking problem.
When the car stops,does it wind over but not start,or does it do nothing and not even attempt to crank over?
Both times the car just doesn't do anything not even attempts to crank.
It could definitely be a problem with the BCM as the BCM basically "gives permission" to the ECU to let the engine start.(immobiliser).The BCM has to first get a signal from the ignition keyfob,which is what the metal contact strips around the ignition switch are for.It will also disable the immobiliser if you press the remotes.If you replace the BCM,you need the matching keyfob.The BCM security code has to match the ignition key security code before the car will start,so the key and BCM have to be a matching pair.
Sounds like a BCM problem, nothing to do with fuel or ECU.
Also you can check for any ECU error codes yourself to see if there is any problems with the ECU.This test is easy to do and only takes a minute or two.Heres a link to a page that shows you how to do it if you dont already know.
---Checking error codes VR/VS (Revised)---
thanks for all your help and replies. yes did have a look at checking error codes, interesting. The bloke I had to take the car to as NRMA towed our car to him and we returned it to as the ECU had a warranty is really nice but I now wonder if he really knows what he is doing. Oh, well have to go pick up car this arvo so will have a further chat about how much this is costing me and whether he is confident that it is nto going to break down again. We generally do most of our work on the car ourselves but weren't sure this time what the problem was and had to get it towed somewhere.
ta
Have you or anyone else replaced the key and ignition barrel assembly? If not, check operation, they get tight with age and need 'encouragement' to work, ie: turning key in ignition quite hard, all the way round sort of thing.
Does your car have an aftermarket security system? My VR does and occasionally it won't turn over, or will start and then stall. Disconnecting negative battery cable for 10 mins will make sure all capacitors lose their charge and hopefully, any confusion about their 'purpose.' A bit like restarting windows when it gets buggy.
Also, check your DFI module under your coil packs. My car would start, run, then run very rough. Replaced DFI, NOT fuel pump. No more probs! yay.
funny you mention that yes the ignition barrel was replaced beginning of last year with a new barrel and key. I assume my car has original security system. Replaced the coil pack half way thru last year as car was running rough been running great up until this problem occurred.
Originally Posted by ourhouse4
Is the security light still flashing when you attempt to crank?
Donating Member
This is a long shot but has happened before - the oil pressure switch forms part of the fuel pump wiring circuit - if the car has recently been degreased, water/degreaser can enter the oil pressure switch and cause it to short out internally....and blow the same fuse as the FP.
"If anyone disagrees with anything I say, I am quite prepared not only to retract it, but also to deny under oath that I ever said it." --T. Lehrer
"The secret of success is sincerity. Once you can fake that you've got it made." -- Jean Giraudoux
Well got the car back yesterday after having another genuine fuel pump put in (one previous that they put in was an aftermarket pump). All good until drove around a round about and the car just cut out again. Was able to get it going again but then later drove it again and it cut out again, managed to get it to the side of the road and then call for NRMA they tell me I am out of fuel huh had a 1/4 of tank in it (car was on an angle at kerb). The mechanic thinks there could be a blockage in one of the pipes near the fuel tank which could be making it cut out just don't know. So put more fuel in it and low and behold it starts but has a flat battery now. I am ready to put a match to.
Did notice that my car was very low on oil could this make the car stop or anything?
Donating Member
The fuel pump may have been installed incorrectly and is not sitting in the swirl pot or the fuel return hose has been broken or dislodged - not uncommon.....this causes very similar problems. Do a search as it's been covered many times.
"If anyone disagrees with anything I say, I am quite prepared not only to retract it, but also to deny under oath that I ever said it." --T. Lehrer
"The secret of success is sincerity. Once you can fake that you've got it made." -- Jean Giraudoux
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