starter motor wiring

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mattfletcher

New Member
Posts
147
Location
walsall, west midlands
Hi guys, the other day, my p38 4.0 wouldnt start, no cranking , no clicking, nothing. So took start motor off and bench tested it, its ok, so I put it back on and checked for power. Got permanent live, but no cranking live, anyone else come across this problem and fixed it? Just starting to strip the dash down to check power on the back of the ignition.
 
matt befor you start pulling it apart, is it a gems engine. pre 1999. as it could be out of sync, you need to plug in a code reader first see what you get..
 
Its a 1995, I can here something clicking uner the drivers seat when I finish cranking, I had similar problem every now and again, but Ive always been able to switch it on and off a couple of times and then it would crank over. Sandy t, Ive tried moving the selector up and down to see if it would make a difference but it doesnt. Datatek, what colour and where about are they located in the fuse box? Under the seat fuse box?
 
mattfletcher said:
Its a 1995, I can here something clicking uner the drivers seat when I finish cranking, I had similar problem every now and again, but Ive always been able to switch it on and off a couple of times and then it would crank over. Sandy t, Ive tried moving the selector up and down to see if it would make a difference but it doesnt. Datatek, what colour and where about are they located in the fuse box? Under the seat fuse box?
Click to expand...
Engine compartement fuse box, check for signs and smells of burning as well as the ignition relay. Check the lid of the fuse box interior for the relay or oners manual.
 
Datatek makes a good point I had all sorts of strange electrical oddities one being it would crank but not fire as well as others all down to internal corrosion of the fuse box in the engine compartment I opened the whole lot up and had dozens of dry joints relay 7 is a fav to burn out but it does cause lots of problems that you would associate with the becm
 
Also, dont know whether its supposed to say it, but when you open the door it says ignition key in on the display and when you take the key out??? Whether that is related to the problem???
 
With a problem like this and before you dismantle anything, there are a few checks that you can do from the comfort of the drivers seat.
Switch on the ignition and watch the amber check engine lamp. If it comes on then this is the gems ecu talking to becm saying saying it is happy with the immobilzation code. If this is the case then forget about resynking the key to the car or the becm to gems or using the eka code.
Assuming, the lamp flashes, switch on the interior lights and try to crank the engine. Does the interior lamp dim, if yes then the starter solenoid is working and sending volts to the starter motor. If it is, then the problem is either the starter is not getting enough volts or the motor is faulty or jammed.
If int lights don't dim, check the starter motor relay (I think it is the smallest one in the fusebox), see if it clicks. If it does not, make sure Ipack is saying N or P. See if relay is getting the correct inputs, measure voltage between the 2 smaller terminals in the fusebox where the relay goes and see if you get 12V when you turn key to crank. There are a lot of checks that can quickly be made before you need to pull things apart.
 
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Right, Ive had a quick look at the relays in the engine compartment and swapped the ones around that my autodata said are for the starter realy and ignition circuit relay. And still nothing?? Theres alot of clicking happening in there when the ignitions turned to crank but naff all else. Have I checked the right relays, they were yellow ones that I swapped round?
 
mattfletcher said:
Right, Ive had a quick look at the relays in the engine compartment and swapped the ones around that my autodata said are for the starter realy and ignition circuit relay. And still nothing?? Theres alot of clicking happening in there when the ignitions turned to crank but naff all else. Have I checked the right relays, they were yellow ones that I swapped round?
Click to expand...

Not familier with the petrol engined stuff, but the relays should be listed under the cover, in your owners manual and in RAVE:D Could be a fuse box problem. Are you sure it is not just a case of needing a re-sync?
 
Dont know, ignition comes on and Ive resynced the fob when I had the battery disconnected to remove the starter. I done that by locking it with the key and pressing the lock button, then unlocked it with the key and pressing the unlock button. Ive had engine immobilised on the dash previously a few months back. Im thinking now that ignition is ok as when you turn key to crank the radio and ignition lights go off as it would if it was cranking
 
had a look today and removed the starter relay. I had two plus feed and two earth feeds. I then power probed the terminal five on the fuse box that was reading an earth. The starter engaged. So from the fuse board to the starter everything works. Before anyone says I have swapped the relay a numerous of times with other ones in the fusebox and still the same. So now I need to know whether the loom runs. Ignition, to ecu, to realy, to starter. Or ignition, to relay, to ecu, to starter. Other than that I was looking at stripping the coweling off the steering column to check for power at the back of the ignition barrel, but how are you supposed to remove the two screws from the bottom cowelling when they are stuck under the dfashboard frame?
 
The ignition switch, does not have 12volts going to it (it uses gnd switching), meaning that when the ignition is switched on, the becm receives a gnd signal from the ignition sw. Likewise when you go to crank, the ign sw sends a gnd to the becm. When the becm receives this gnd, it checks if you are in Park/Neutral and that car is not immobilised. Thats why you need to make sure the message centre says N or P and the amber check engine light comes on when ignition is on.
The becm will then send a gnd to the starter motor relay when it wants to crank the engine. If you want to check the ignition switch signals do it at the becm and you can then at same time check the becm output. Did the engine fire up when you cranked it?. This problem is not linked to the key in sw.
 
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