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ABS sensor=crank sensor?

Ditchdigger

Ditchdigger

Literally Clueless
Joined
May 20, 2020
Member Number
485
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102
I have an old Mercedes diesel. Tach not working. Crank sensor is missing. Can an ABS sensor be used instead? Kind of the same concept,no?
 
The older inductive ABS sensors might work. A more modern one with an IC in it won't.
 
tsomctl said:
The older inductive ABS sensors might work. A more modern one with an IC in it won't.
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Could you explain that but pretend you are talking to a small child or an idiot? :grinpimp: What is an IC? Inductor coil? How would I know the difference?
By the way, thanks!
 
Get an ABS sensor from a non-Eureopean vehicle from before 2000.

The older style are just a steel slug with a wire coiled around it, which is exactly how older crank position sensors are also made.

The newer style are hall effect and have an intergrated circuit inside it.

You can tell the difference by hooking up an oscilloscope to a running vehicle and looking at the waveform while spinning the tire. The older style will produce an AC sine wave. The newer style will produce a square wave that is always positive.

Might just be easier to get an older crank position sensor or cam position sensor (just make sure it's 2 wire. A 3 wire one will be a hall effect sensor and needs a 5 volt reference).
 
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tsomctl said:
Get an ABS sensor from a non-Eureopean vehicle from before 2000.

The older style are just a steel slug with a wire coiled around it, which is exactly how older crank position sensors are also made.

The newer style are hall effect and have an intergrated circuit inside it.

You can tell the difference by hooking up an oscilloscope to a running vehicle and looking at the waveform while spinning the tire. The older style will produce an AC sine wave. The newer style will produce a square wave that is always positive.

Might just be easier to get an older crank position sensor or cam position sensor (just make sure it's 2 wire. A 3 wire one will be a hall effect sensor and needs a 5 volt reference).
Click to expand...
I can’t thank you enough. :beer::beer::beer:
 
total newb said:
Conceptualy, yes.

Physicaly, probably not.
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It’s a pretty simple bracket that bolts to the block above the harmonic balancer. The sensor just bolts to that. It’s a very simple system but parts are OEM parts are becoming scarce from the Fatherland.
 
AKnate said:
If you figure out a cheap one, looks like you'll have a good side line.

Ebay wants $600 for a factory one.

At that price I'd be swapping in a SBC or 4BT :laughing:
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😬
I COULD just run a boat tach. I bloody love this thing. Cougars appreciate it. Honestly.
 
Well! It works. Held it next to harmonic balancer and it read RPM.now just to get it to sit just right in bracket as far as spacing.
 
IMG_6405.jpeg

Works like a charm. Cruise still not working but it’ll come. Thanks for the help!
 
Ditchdigger said:
Well! It works. Held it next to harmonic balancer and it read RPM.now just to get it to sit just right in bracket as far as spacing.
Click to expand...

What does it pick up from the balancer to "trip" the sensor and get a reading?

I've been scheming on a cheap way to add a tack to the D721 Kubota engines in my mini ex. and figured there had to be an easier and cheaper way fuel line pulse transducer thing that Tinytach does. Bonus points if I could use something that put out the same signal that the digital gauge it has is looking for. (They use the same digital gauge that's on the gas version of the machine.)
 
bgaidan said:
What does it pick up from the balancer to "trip" the sensor and get a reading?

I've been scheming on a cheap way to add a tack to the D721 Kubota engines in my mini ex. and figured there had to be an easier and cheaper way fuel line pulse transducer thing that Tinytach does. Bonus points if I could use something that put out the same signal that the digital gauge it has is looking for. (They use the same digital gauge that's on the gas version of the machine.)
Click to expand...

You can literally use a scrap square cut bit of steel.
 
bgaidan said:
What does it pick up from the balancer to "trip" the sensor and get a reading?

I've been scheming on a cheap way to add a tack to the D721 Kubota engines in my mini ex. and figured there had to be an easier and cheaper way fuel line pulse transducer thing that Tinytach does. Bonus points if I could use something that put out the same signal that the digital gauge it has is looking for. (They use the same digital gauge that's on the gas version of the machine.)
Click to expand...
It just has a metal dowel sticking out of the balancer.
 
Most diesel tachs use a simple magnetic pickup reading a small magnet on the crank or go to a terminal on the alternator which is just a gap on one of the three AC windings inside.

I don't think the alternator on a small engine would have that. Certainly could split the alternator and make a little piggyback wire on the stator for that feed.

A good aftermarket tach would work with a magnetic pickup reading the starter teeth. Some bellhousings have threaded holes for these or you could add one. You just want to make sure your tach has the ability to program for this.
 
Sorry. Didn’t see the responses. I’ll get some pictures if possible this week. I used the original bracket, and a wheel sensor from a 2000 Yukon I had kicking around . I had to do some weld fab on the bracket but it turned out great. I have a ground issue to find as the tach goes down to 500 when I put on the turn signal.
The shit on the dash is someone’s poor attempt at repair in the last 44 years.
Btw, if anyone has a lead on a headlight bezel for an 80 Mercedes 300 SD, I’d appreciate. Has to be an SD as both lights are same size.
 
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