Any Auto Electricians on line?
Discussion
Hi, i'm having trouble rectifying an electrical fault on my Mondeo Tdci 2.0l 130ps Ghia X (2004).
I have tried a multitude of things, and am reasonably competent (as an Engineer at one of the largest car companies), however sparks are not my 'thing'!
I have a short cicruit somewhere which causes the fuse for the wash / wiper / Auto lights to blow. I have removed the loads from the circuit until the fuse stopped blowing (or no power was being drawn across my test rig). The wiper motor seems to be the cause, however I have tried 2 different wiper motors now and the problem returns with each one.
I have swapped like for like relays to ensure these are not faulty.
I have 3 live pins at the front wiper motor plug. One is switched from the stalk, slow wipe (confused why this would be live when in the off position? Is this for the park function?) and then 2 other live feeds which according to the wiring diagram come from the relay. I can stop the power to these by removing the GEM.
Can anyone help?
I have tried a multitude of things, and am reasonably competent (as an Engineer at one of the largest car companies), however sparks are not my 'thing'!
I have a short cicruit somewhere which causes the fuse for the wash / wiper / Auto lights to blow. I have removed the loads from the circuit until the fuse stopped blowing (or no power was being drawn across my test rig). The wiper motor seems to be the cause, however I have tried 2 different wiper motors now and the problem returns with each one.
I have swapped like for like relays to ensure these are not faulty.
I have 3 live pins at the front wiper motor plug. One is switched from the stalk, slow wipe (confused why this would be live when in the off position? Is this for the park function?) and then 2 other live feeds which according to the wiring diagram come from the relay. I can stop the power to these by removing the GEM.
Can anyone help?
There is more to the circuit than relays and motors. Dont forget the wiring.
A short there or poor connection/corrosion can cause an overload and blow fuses. Not always easy to find, and really a case of digging deeper.
Try manually powering the wipers and measuring how much current they draw.
A short there or poor connection/corrosion can cause an overload and blow fuses. Not always easy to find, and really a case of digging deeper.
Try manually powering the wipers and measuring how much current they draw.
How do i test current draw with the wiper motor manually powered?
Are you an Auto Electrician by any chance?
I have done a ton of diagnostic work on this problem, and the fuse consistently blows with the front wiper motor connected (and not without), but I have tried 2 alternative motors which gave the same effect. I have now disconnected every other load point on the circuit to the best of my knowledge.
I've buzzed out pretty much all connectors and have inspected all connectors. Can't see any sign of corrosion / shorting / burning etc, and the only circuits to earth seem to be the terminals which should go to earth. Only exception is a power feed from the fuse in question to the stalk which seems to go to ground with the fuse in (1.6ohms resistance), but not when fuse is out...
Current to the relevant connector is 16A, which looks fine for a 20A fused circuit.
Are you an Auto Electrician by any chance?
I have done a ton of diagnostic work on this problem, and the fuse consistently blows with the front wiper motor connected (and not without), but I have tried 2 alternative motors which gave the same effect. I have now disconnected every other load point on the circuit to the best of my knowledge.
I've buzzed out pretty much all connectors and have inspected all connectors. Can't see any sign of corrosion / shorting / burning etc, and the only circuits to earth seem to be the terminals which should go to earth. Only exception is a power feed from the fuse in question to the stalk which seems to go to ground with the fuse in (1.6ohms resistance), but not when fuse is out...
Current to the relevant connector is 16A, which looks fine for a 20A fused circuit.
DF1 said:
How do i test current draw with the wiper motor manually powered?
Are you an Auto Electrician by any chance?
I have done a ton of diagnostic work on this problem, and the fuse consistently blows with the front wiper motor connected (and not without), but I have tried 2 alternative motors which gave the same effect. I have now disconnected every other load point on the circuit to the best of my knowledge.
I've buzzed out pretty much all connectors and have inspected all connectors. Can't see any sign of corrosion / shorting / burning etc, and the only circuits to earth seem to be the terminals which should go to earth. Only exception is a power feed from the fuse in question to the stalk which seems to go to ground with the fuse in (1.6ohms resistance), but not when fuse is out...
Current to the relevant connector is 16A, which looks fine for a 20A fused circuit.
I'm not an auto electrician, but testing that should not be difficult. ALthough your limitation may be that a lot of cheap multimeters only read to 10AAre you an Auto Electrician by any chance?
I have done a ton of diagnostic work on this problem, and the fuse consistently blows with the front wiper motor connected (and not without), but I have tried 2 alternative motors which gave the same effect. I have now disconnected every other load point on the circuit to the best of my knowledge.
I've buzzed out pretty much all connectors and have inspected all connectors. Can't see any sign of corrosion / shorting / burning etc, and the only circuits to earth seem to be the terminals which should go to earth. Only exception is a power feed from the fuse in question to the stalk which seems to go to ground with the fuse in (1.6ohms resistance), but not when fuse is out...
Current to the relevant connector is 16A, which looks fine for a 20A fused circuit.
You can buy a cheap AC/DC clamp meter for around £25 of egay though.
http://www.ebay.co.uk/itm/New-UNI-T-UT203-AC-DC-AM...
Or Maplin sell these which are quite handy, but perhaps less versatile.
http://www.maplin.co.uk/automotive-current-tester-...
That said, I guess the fact it is blowing fuses does indicate it is drawing more than it should.
Does it blow on initial startup ? Sure you have the correct fuse rating ? What do you mean by 16A to the connector, so have you actually measured the current draw when they are working ?
With the motor only connected and powered up does it blow ? ie no wipers or linkage attached ?
16A at the connector is testing across the pins with the stalk switched to send power. Not with motor on. If i connect the motor it blows every time, but i have tried 2 alternative motor's and they both do the same. I am getting power to 3 pins at the connector, one from the stalk (even when off) and the other two from relay & GEM. (Fuse still blows with stalk, GEM and relay removed)
If i power the ignition with the stalk on fast wipe it will run for about 5 seconds. last night I saw a spark at the motor casing as it blew, which has led me full circle to motor again...
car is 9 years old, but has not skipped an electrical beat in teh 18 months i've had it. I've checked the loom around any moving parts and there is no sign of damage or wear. No sign of shorts or burning at any connectors, and I have buzzed each connector to earth to check for shorts.
If i disconnect the front motor, the rest of the sytem work fine.
I'm testing with a Fluke 111, so it will go to 20A and OL, so it should be fine, but i am not sure physically what to do to test with the motor on (which I can't do without blowinga fuse anyway).
If i power the ignition with the stalk on fast wipe it will run for about 5 seconds. last night I saw a spark at the motor casing as it blew, which has led me full circle to motor again...
car is 9 years old, but has not skipped an electrical beat in teh 18 months i've had it. I've checked the loom around any moving parts and there is no sign of damage or wear. No sign of shorts or burning at any connectors, and I have buzzed each connector to earth to check for shorts.
If i disconnect the front motor, the rest of the sytem work fine.
I'm testing with a Fluke 111, so it will go to 20A and OL, so it should be fine, but i am not sure physically what to do to test with the motor on (which I can't do without blowinga fuse anyway).
stevieturbo said:
How can you possibly see 16A of current flowing if the motor isnt even turned on ?
That makes no sense whatseover
If this problem made sense i would have fixed it by now mate, and i wouldn't be on here asking for help (which your last post isn't by the way). That makes no sense whatseover
How do I test the current on a motor which blows the fuse every time you turn the ignition switch on? If it blows without the motor being 'switched on' it suggests that the motor isn't the fault (it's whatever is sending the power). If it doesn't blow when you disconect the motor is suggests the motor IS at fault. Doesn't it?
In answer to your last post... I had power to the motor connector (because the ignition and stalk were switched to 'on', there was a fuse in the fuse box and the motor was not connected so it hadn't blown the fuse) and I put one tester lead into the connector pin and the other tester lead to earth, i got a reading of 16.3 with my multi meter set to measure amps.
Not to worry anyway, I was hoping that someone on here may be able to advise things to test and try and perhaps 'how to test' the things that I didn't understand. I'll have a go at reading the current with the motor powered up remotely. To be fair, the chances of 3 completely different motors and mechanisms being seized / tight / drawing too much current is pretty slim... If they are I might stick a fiver on the lottery...
DF1 said:
If i power the ignition with the stalk on fast wipe it will run for about 5 seconds. last night I saw a spark at the motor casing as it blew, which has led me full circle to motor again...
.
Theres a clue. I would suspect that you have a 12 volt supply that is being grounded once the wiper reaches the park position. You know what connectors have 12 volts on them, so disconnect the plug and measure the resistance to ground between these pins on the motor, but try and do it in both the parked and non parked positions if you can rotate the motor in some way, and see if anything shows near 0 ohms. A DC motor will only show the actual resistance of the windings with a test meter when its not turning (The effective resistance goes up when the motor is running), so all the the resistance values you measure are going to be pretty low. A bit of ohms law will give you some basic pointers. If say a 20 amp fuse blows at 12 amps R=V/I so 12/20 =.6 of an ohm or less to ground. The motor windings will be a bit more at a guess, but it will all be pretty close so the readings will need to be accurate. Id suspect there is 12 volts on a line that should be ground somewhere or vice versa thats feeding the motor park switch..
DF1 said:
If this problem made sense i would have fixed it by now mate, and i wouldn't be on here asking for help (which your last post isn't by the way).
How do I test the current on a motor which blows the fuse every time you turn the ignition switch on? If it blows without the motor being 'switched on' it suggests that the motor isn't the fault (it's whatever is sending the power). If it doesn't blow when you disconect the motor is suggests the motor IS at fault. Doesn't it?
In answer to your last post... I had power to the motor connector (because the ignition and stalk were switched to 'on', there was a fuse in the fuse box and the motor was not connected so it hadn't blown the fuse) and I put one tester lead into the connector pin and the other tester lead to earth, i got a reading of 16.3 with my multi meter set to measure amps.
Not to worry anyway, I was hoping that someone on here may be able to advise things to test and try and perhaps 'how to test' the things that I didn't understand. I'll have a go at reading the current with the motor powered up remotely. To be fair, the chances of 3 completely different motors and mechanisms being seized / tight / drawing too much current is pretty slim... If they are I might stick a fiver on the lottery...
Well then you're overlooking the blatantly obvious and wasting time and money messing about changing motors. IF, and it's a big IF, there is actually a current flow of 16A without the motor even plugged in, that suggests very clearly there is little wrong with the motor !How do I test the current on a motor which blows the fuse every time you turn the ignition switch on? If it blows without the motor being 'switched on' it suggests that the motor isn't the fault (it's whatever is sending the power). If it doesn't blow when you disconect the motor is suggests the motor IS at fault. Doesn't it?
In answer to your last post... I had power to the motor connector (because the ignition and stalk were switched to 'on', there was a fuse in the fuse box and the motor was not connected so it hadn't blown the fuse) and I put one tester lead into the connector pin and the other tester lead to earth, i got a reading of 16.3 with my multi meter set to measure amps.
Not to worry anyway, I was hoping that someone on here may be able to advise things to test and try and perhaps 'how to test' the things that I didn't understand. I'll have a go at reading the current with the motor powered up remotely. To be fair, the chances of 3 completely different motors and mechanisms being seized / tight / drawing too much current is pretty slim... If they are I might stick a fiver on the lottery...
it does however suggest there is some serious wiring or control unit faults.
And how do you test the motor ?? Simple, just test the thing !!
It doesnt have to be attached to a car to test you know. Get a battery, some wires and apply 12v to the relevant terminals. You could do this near the car, in the house, in the garage, anywhere really.
Keeping changing motors when it's quite obvious the motor isnt at fault is just daft. Or at least without even testing the motor.
When offering help over the web like this, it does assume the person on the receiving end does have some knowledge or common sense to test and make some sense of the test results.
Edited by stevieturbo on Wednesday 11th January 21:33
Thanks 'Blitzracing', i appreciate the sharing of your knowledge. That's how we learn and develop as people. I have fixed the problem tonight, but thanks anyway, it turned out to be a fault of two components. Both the wiper motor and the GEM unit. Sometimes a step back and some logical thinking is what you really need.
Stevieturbo, i clearly state at the start of the thread that I am not an electrician. But given some guidance and knowledge I have yet to find much that I can't do. I applogise for not being as 'skilled' at auto electronics as you, but then i guess we all have our strengths and weaknesses?
Anyway, appologies if I have caused anyone any frustration in asking for help on a renowned forum like Piston heads. I thought that of all the places to find some like minded knowledgable people, that this would be it....?
Stevieturbo, i clearly state at the start of the thread that I am not an electrician. But given some guidance and knowledge I have yet to find much that I can't do. I applogise for not being as 'skilled' at auto electronics as you, but then i guess we all have our strengths and weaknesses?
Anyway, appologies if I have caused anyone any frustration in asking for help on a renowned forum like Piston heads. I thought that of all the places to find some like minded knowledgable people, that this would be it....?
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