Just another round of BS - how to test cam sensor?

Energy One

roadie1389

Well-Known Member
Well, tidied up the last bit and tried to fire up the dog and just cranks. I think it is in the ignition.

New RIP
04 107 stock TH ignition with CAM sensor (not crank).

When you turn the power on the ignition module red LED goes on and stays on. If memory was correct the red LED should go off after a few seconds. I am thinking that a wire might be crossed on the cam sensor as I did pull the pins from the JST to redo the heat shrink. Yes I should have took pics but red is red right. Anyway I pulled some docs from KMW on how to test a few circuits but they are for testing new bikes with crank sensor. Anybody now how to test the cam sensor?
 

Th3InfamousI

Administrator
Staff member
There's a procedure to test them with a multimeter. You can search on the forum it's available I have seen it I should have saved it somewhere.

I actually own a cam sensor testor that you just plug it in and reads it for you. If you can't find them you can mail it to me and I'll test and shoot it back to you. although they are not super expensive either to just replace so might be a hassle.

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BroadBand

Since late 60's
SEARCH is your best friend....

http://www.bigdogbiker.com/threads/rookie-wrencher-troubled-dog-lengthy-post.30808/#post-429986


1. Disconnect the cam sensor from the ignition module.
2. Take out your trusty multimeter and set it to the RX1 scale.
3. Now while touching the sensor backing plate with the negative meter lead touch the positive meter lead on each of the three wires of the sensor connector (red, black, & green). If you get continuity from the backing plate to any of them the sensor is bad.

If it passes the first test...
1. With your meter still at the same settings touch the positive meter lead to the green wire and the negative meter lead to the black wire. If you get an "open" it's good.
2. Then take the positive meter lead and touch the black sensor wire while touching the negative meter lead to the green wire. In this case an "open" is bad. A reading somewhere around 300 - 750 Kohms is what you're looking for.
 

roadie1389

Well-Known Member
SEARCH is your best friend....

http://www.bigdogbiker.com/threads/rookie-wrencher-troubled-dog-lengthy-post.30808/#post-429986


1. Disconnect the cam sensor from the ignition module.
2. Take out your trusty multimeter and set it to the RX1 scale.
3. Now while touching the sensor backing plate with the negative meter lead touch the positive meter lead on each of the three wires of the sensor connector (red, black, & green). If you get continuity from the backing plate to any of them the sensor is bad.

If it passes the first test...
1. With your meter still at the same settings touch the positive meter lead to the green wire and the negative meter lead to the black wire. If you get an "open" it's good.
2. Then take the positive meter lead and touch the black sensor wire while touching the negative meter lead to the green wire. In this case an "open" is bad. A reading somewhere around 300 - 750 Kohms is what you're looking for.

Thanks. So all the test pass except the "Then take the positive meter lead and touch the black sensor wire while touching the negative meter lead to the green wire. In this case an "open" is bad."

Edit - I took sensor out and connected to a battery. Red +12V, Black -12V and connected DMM to Green and black leads. Ran a screw driver though sensor and no voltage at the green wire. Based on what I believe it should have triggered a +5V voltage when I did this. So it looks like sensor is bad.

Another interesting item is if I only plug the power leads up to the sensor the ignition module light comes on and then turns off. Anybody got a spare working sensor laying around they would be willing to loan/sell cheap?
 
Last edited:

Th3InfamousI

Administrator
Staff member
Thanks. So all the test pass except the "Then take the positive meter lead and touch the black sensor wire while touching the negative meter lead to the green wire. In this case an "open" is bad."

Edit - I took sensor out and connected to a battery. Red +12V, Black -12V and connected DMM to Green and black leads. Ran a screw driver though sensor and no voltage at the green wire. Based on what I believe it should have triggered a +5V voltage when I did this. So it looks like sensor is bad.

Another interesting item is if I only plug the power leads up to the sensor the ignition module light comes on and then turns off. Anybody got a spare working sensor laying around they would be willing to loan/sell cheap?
Well, my other question is did you ever move the cam sensor during the install? The cam sensor has to be in the specific location or else it will be out of time and potentially won't start.

I mark the cam sensor position with a sharpie when I remove mine. But you can usually line it up with the markings from the bolts too.

You can order a new cam sensor from Curtis at Wild Steed Worx or you can just order a Harley cam sensor for a softail EVO same part.

Also I've never tested it with a battery, but I don't think you will get voltage until it hits the sensor not 100% sure here. I don't think it's always showing power it sends waves back to the module to send fire to the coils.

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roadie1389

Well-Known Member
Well, my other question is did you ever move the cam sensor during the install? The cam sensor has to be in the specific location or else it will be out of time and potentially won't start.

I mark the cam sensor position with a sharpie when I remove mine. But you can usually line it up with the markings from the bolts too.

You can order a new cam sensor from Curtis at Wild Steed Worx or you can just order a Harley cam sensor for a softail EVO same part.

Also I've never tested it with a battery, but I don't think you will get voltage until it hits the sensor not 100% sure here. I don't think it's always showing power it sends waves back to the module to send fire to the coils.

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Nope never took the sensor out. This bike had all kind of wierd issues at once. I am going to replace the sensor.
 

Th3InfamousI

Administrator
Staff member
Nope never took the sensor out. This bike had all kind of wierd issues at once. I am going to replace the sensor.
You can find them on eBay for $20-30 usually. Just won't have the JST. Might give Donna a call they probably have them with the JST and price will probably be the same.

Depending on your funds you could upgrade the ignition to a programmable single fire unit and coil at this point as well. Might be worth a thought just incase your ignition module is shot as well.

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Sven

Well-Known Member
Based on what I believe it should have triggered a +5V voltage when I did this. So it looks like sensor is bad.
Based on watt I know, a crank, speed, and cam sensor are basically the same AC producers "as like" a rotor and stator. But on a lower scale in voltage output. Yes, an IC [integrated circuit] receives 12v and the voltage ends there. Out the other leg(s) is 5v; wired up to a resistor(s) and or capacitor(s) you have 3 variables to play with as in timing thresholds. A clock would hold a time. A stopwatch would have its own type of timing thresholds. Fuel injectors would have their own and so on.

In the processing, the volts may shoot as HIGH as 5.5v or a value of 1 read in binary. Getting technical in the basics of it again, the running LOW range is considered turned OFF or steps down to 0.8v in range or is now written as 0 in the binary conversion. Lastly, 1.2v is noise so that range is not normally used.

So withundreds of words covering my ass as the steps step to the music, watthell you throwing 12v thru an AC wire for? It needs to have a magnet pass by it to produce AC. I'm sure you could hook up 12v to it like you did, but have the ohm meter set at 20v, see if the wires have not broken inside is one way to check it.

But I think the test is to find its peak "ouput" voltage and that calls for a peak voltage tool. For argument sake, a cam sensor should push out 2.+v. Anything under that number is a 'signal out of range.' And that test is not a bench test with a 12v source. I would not cause the tiny coil to act as a fuse or overheat it with the wrong watts sucking up 12v and that wire strand melts thru its coating, touches the next wire, etc. That test of the tiny AC sensors is to crank the engine so the magnet makes the voltage out past 2+v.


Cam sensor detects which cylinder is 'next to fire.'
Crank sensor is tested with a VOM and a numbered range is the blueprint of that resistance number.
Crank sensor is the 'chain' to running. Without the crank sensor, any computer bike defaults to a 'boat anchor.'

Cam sensor has a 'peak voltage' needing to be met/measured with special tool and a spinning [dead] engine.
Crank sensor came before cam sensor. The logic would be a crank sensor would start the bike, not a cam sensor. I could be wrong in this case.

Variables:
'Last good signal' saved:
a. As bike runs, cam sensor fails while running, last good signal keeps engine running.
b. As bike is turned off, last saved RAM is lost upon grounding, meaning, cycling key off to ground.
c. As bike is keyed back on, might ROM start bike with cam sensor disconnected? With cam sensor in the loop, no good known signal sent, wire short to ground, short internally, it sends a wave not within range so ROM is the backup to keep it running? And that is after 25 or more passes before an (alleged) backup should start it or the processor is not designed that way? It runs in the cheap seats where (more parts) are needed is a bigger motherboard, or a simple flipflop is the process. Meaning, it's either/or.
d. As bike's blackbox sweeps or pings all signals, note light stayed off is it triggered the box as if a good known signal pinged it off. Where is the default ROM to start the bike no cam sensor? Now the question is... will it run with cam out of the loop?
e. As bike works in an ON/OFF kind of flip of the flop, might one remotely ground the one wire, bend any size resistor, meaning, [its legs] into the main wire harness connector and address those other 2 wires.

In theory:
1. This flips the light off and holds the flop.
2. This now sends a single [same over and over] value each time.
3. This should trigger a backup spark past so many revolutions is the AC is not linear anymore.
4. This says I remove plugs, have the spin occur faster, watch the spark come back online with so many spins; the backup shows it sparks [in default mode] and does not need a cam sensor. That or back to a cheap ass processor acting like a crank sensor is either one fails, no backup? BS is why I choose my threads carefully is learn how the processor works as I read the processor built>>> in so many moves.

The OP throws 12v at a sensor... wire in is wire out, sure it would show something broken internally, if not has a certain smell to it; as in burnt caused by induced heat. But the OP does not mention 'smoke' during the test. Lucky?

The OP thinks 5v is sent out the sensor... or whatever the abstract was mentioned, you gotta lift the hood and know "watt parts is parts is" doing... or I'm going to pull your trousers down, look for sand and brush it off wit ha steel brush.

The OP makes an assumption the sensor is bad using 12v, not as suggested is that special tool finding its 'peak value' and spin the shit up is testing a cam sensor.

Signed,

NOLTT
 

Sven

Well-Known Member
you could have already installed a $20 cam sensor and been down the road!
If I had a memory for OR AND NOR gates, memorized the binary system and could read the numbers, I'd know how to wire up a motherboard. I'm not even close. But theory goes, you bought a cam sensor and it wasn't it. Basic theory points the way. I think you grasped some of it looks like. Now you have to either measure shit or throw parts at it.

More like a bad ground>> it was working before the box swap? Light going on and off is not the box, but waiting for input, right?
 

Th3InfamousI

Administrator
Staff member
If I had a memory for OR AND NOR gates, memorized the binary system and could read the numbers, I'd know how to wire up a motherboard. I'm not even close. But theory goes, you bought a cam sensor and it wasn't it. Basic theory points the way. I think you grasped some of it looks like. Now you have to either measure shit or throw parts at it.

More like a bad ground>> it was working before the box swap? Light going on and off is not the box, but waiting for input, right?
Light will turn on and stay on with a WP unit used to turn off with the EHC. Not sure what the RIP unit or DOC does Blinks when hitting start.

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Sven

Well-Known Member
TH ignition with CAM sensor (not crank).
1. Disconnect the cam sensor from the ignition module.
I'm going to put 2 and 2 together and answer my own [backup] question. It was right here. "I have a TH ign with CAM (not crank) is' '1. Disconnect CAM sensor from ign module." Thus concludes no backup, no crank sensor being the backup or one being used. Again the theory is; who needs a crank sensor, if I still use the same spin, just less revolutions in count off, right? This now answers and explains a single sensor trigger >> either off the crank or off the cam = Boat Anchor.
 
If I had a memory for OR AND NOR gates, memorized the binary system and could read the numbers, I'd know how to wire up a motherboard. I'm not even close. But theory goes, you bought a cam sensor and it wasn't it. Basic theory points the way. I think you grasped some of it looks like. Now you have to either measure shit or throw parts at it.

More like a bad ground>> it was working before the box swap? Light going on and off is not the box, but waiting for input, right?
Sven you are what in my younger days was considered a true mechanic, an individual with the knowledge to locate and fix the problem. These days many of ( most of) the Techs are simply parts replacement experts. Thanks for sharing your knowledge with us
 
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