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Post by bighec on Apr 11, 2015 20:36:44 GMT
Good evening,
Hoping there are some clever wigs out there because I am stumped,. Bit of a wiring conundrum for to solve. I am wiring up the brake reservoir / handbrake switch warning light. The dash is a ACEWELL unit with the warning lamps grounded to illuminate them.
To comply with the IVA my understanding is that with a low brake reservoir the Brake warning light must come on. Driver must also be able to test the operation hence the handbrake switch. There are two wires coming from the reservoir. Neither at any position have continuity with earth.
With the float down, ie tank empty, there is continuity between both wires.
With the float up, ie tank full, there is no continuity between the two tank wires.
So, easy I think, one wire from the tank to earth, the other to the ACEWELL UNIT brake light connection and T'd off to and one to the handbrake switch.
So in theory when the handbrake is pulled, or the tank is low, the dash light is grounded to the earth and the light illuminates. Except that doesn't happen, with the connections made as described, the brake light is illuminated and wont go out regardless of whether the tank is full or empty or the handbrake is up or down?? yet if I physically remove the wire from the earth to the reservoir the light goes out??
Any suggestions as it doesn't made any sense to me. I am not using the standard loom, I have rewired completely and all other systems so far have gone without hitch.
Cheers
Hec
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Post by gwnwar on Apr 12, 2015 7:37:25 GMT
So if only the hand brake switch is wired up it works as it should handle up light on handle down light off. If so problem is with the fluid sensor. the blue/yellow wire in sensor should go to the warning lamp and the black on sensor to ground. Does the float on sensor float come up with fluid? The Blue/Yellow only supply ground.
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Post by bighec on Apr 12, 2015 21:04:17 GMT
So if only the hand brake switch is wired up it works as it should handle up light on handle down light off. If so problem is with the fluid sensor. the blue/yellow wire in sensor should go to the warning lamp and the black on sensor to ground. Does the float on sensor float come up with fluid? The Blue/Yellow only supply ground. Thanks for the reply. That's exactly how she's wired. It's the fluid level switch but there's some magic happening. Can't understand how the switch has no continuity between wires when the float is up when (tested with multimeter) yet still provides earthing to the dash when wired in. Doesn't seem to be logical to me. Unless the switch is affected by the minimal current when the connection is made go dash, it's a mystery to me . All I can get my head round is some sort of latching of the contacts when there is current through her with the dash illuminated ?
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Post by gwnwar on Apr 12, 2015 22:01:12 GMT
You do have 2 different wires to the switch one to frame other to lamp only. How about using a test light 1 side to 12v other to the wire to dash unit from the switch.. check right before it plugs into dash unit. Move float up/down see if light goes on/off.. Also take wire from hand brake out of test at dash unit or were spliced in.... Take dash unit its self out of the test.. What is ground side (black wire don't know if it makes a difference which wire you supply ground to) grounded to.. If both hand and level sensors work by themselves with test lamp then connect leads together and retest with test lamp. if good hook to dash unit. are you sure you don't have a small piece of wire touching another..
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Post by bighec on Apr 17, 2015 6:26:33 GMT
I have tried the handbrake direct to the dash unit. Works exactly as it should. Tried the fluid tank with a test lead ie a 12 volt led. The led behaves as the dash does ie it maintains a connection to the earth, remains lit, regardless of where the switch is or which wire from the tank is to the earth.
My conclusion is that the fluid tank perhaps works on resistance reading rather than a simple on of switch. Tried the multimeter on the resistance reading. Between both wires on the tank there is a high resistance with the float up and minimal with it down. Now to figure out a circuit that breaks a connection based on a resistance higher than a specified level....
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Post by gwnwar on Apr 17, 2015 23:53:12 GMT
Are you saying you put a 12V supply to one of the wires on float switch and the other wire to the dash unit?? That would put 12v to the dash unit.. All the float switch does is supply a ground to the dash unit.. no 12v to float only ground the black wire to frame and other wire to dash lamp with hand brake wire..
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Post by bighec on Apr 18, 2015 19:13:36 GMT
Hi,
No not at all. The Dash unit provides the 12 volt for the circuit. As you quite rightly point out, all the float switch does is provide a connection to earth. But here in lies the problem. Its not behaving as you might expect.
Two wires from float switch . Tested with continuity tester on multi meter. Float Down = continuity. Float up = no continuity (as you would expect).
So, first test the dash light, ground the connection, brake warningi light illuminated. Break the connection light goes out. So connect one wire from float switch to earth, the other wire to dash. Problem, regardless of what position the float is in the dash light illuminates and remains on until such time as you physically remove the connection to the earth. It makes no difference which wire from the float switch is connected to earth or dash. Either way the result is the same. The light remains on.
So as a final test to ensure that the dash unit is not the problem I tried a simple 12v test light. Positive to battery. Negative to one side of the float switch, earth to the other. The results are exactly as if the dash unit is connected, ie the light remains illumintated regardless of what position the switch is in.
In summary, the float switch, when tested with the multi meter, appears to function as it should, however when the circuit is energised, ie connected to any 12v function, conntinuity is always present regardless of the position of the switch. Weird....
I suspect the multi meter will be putting such a tiny current through the switch and the resistance is so high with the float up that it appears as though there is no continuity when in actual fact there is continutiy albeit with a very high resistance.
.. These things are sent to try you.
Cheers
Hec
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Post by gwnwar on Apr 18, 2015 23:02:55 GMT
Sounds like the float switch is not shutting off ground source.. Question is the wire from the float to the dash in a harness or just a single free wire.. If in a harness try a free placed wire between float and dash unit.. so far it sounds like a bad switch..
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Post by bighec on Apr 19, 2015 3:30:10 GMT
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