My car has an intermittent check engine light.
It is being triggered by the shaft input speed sensor. This sensor is located between the engine and transmission, and they have to be removed from the car to replace it.
A daunting task to be certain.
I assume Cadillac has used a hall sensor to for this application. As it is an intermittent problem I am thinking that the hall sensor is getting too hot. Either due to age, or it may be close to failing.
Rather than remove the drivetrain from the car, I am thinking that if I can reduce the load on the sensor it won't get so hot.
I am thinking that placing a transistor between the sensor and the ECU will reduce the load on the sensor. Kinda like a gain stage of an amplifier. I would think that I could then reduce either voltage or current to the sensor and wouldn't get so hot.
Is my Idea sound? If not, can anybody tell me a solution which may work?
If you know what circuitry I might try, along with values it will be greatly appreciated.
Thank you.

 

Likely will not work.
What is the exact sensor part and/or a link to the exact part.

I would first check all electrical connections as they have a higher intermittent failure rate than solid state electronics.

 

Thanx for replying!
From what I have gathered on the Cadillac forum, this is a pretty common failure on my year and model. The generally popular solution seems to be "sell the car". My car is in otherwIse excellent shape, so I am hesitant to do this.
Here's a link to the sensor I am referring to:
https://www.rockauto.com/en/moreinf...h+NzsrjWB3RyFvBohllP36IhqHw2rjwPYK6hbcWxoAuvD

 

Get an OBD-ll scanner from an Auto-Parts-Store so that You can reset the Light.
Make sure that it has a "Reset" function, not all of them do.
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I know how to do a reset. By the way, with a Cadillac you don't even need the scanner. It can be doen from the car's own menu.
I need to fix the problem. So, what I need is somebody knowledtgeable who understands how to reduce the load on the sensor.

 

I need to fix the problem. So, what I need is somebody knowledtgeable who understands how to reduce the load on the sensor.

That presumes that the load on the sensor is the cause of the problem, which I consider extremely unlikely.

How have you determined that this is the root cause?

 

Your Car-Payments have not ended just because You don't have to send your Money to a Bank.
Your Car-Payments will never end.

I keep my Cars/Trucks for ~20 to ~30-years,
( or until they sustain excessive damage from some stressed-out Clown who can't drive ),
because I started learning how to repair or modify them at around age ~14.

You can either ignore the Trouble-Code,
or cough-up the ~$1,800.oo Dollars to have a Cadillac-Dealer solve the problem.
If the Dealer doesn't get it right, You don't pay for subsequent visits, until they do get it right.

As a very competent BMW-Trained Electrical and Drivability Specialist,
I would bet that any Self-Generated Heat in the Sensor has nothing to do with the problem.

The amount of Current handled by the Sensor is minuscule,
and therefore generates almost zero-Heat.

You have said that You have been participating in some Forums
discussing the problems You are experiencing.
What was the consensus ?
Who solved the problem, and how ?
If nobody solved the problem, then it's time to keep on looking for a solution.
Since You say that this is a "known-problem", the solution can't be far behind.

The solution will not be to create any kind of Buffer-Amplifier for the Sensor.
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A sensor is quite unlikely to have enough of a load to generate ANY excess heat. Your diagnostic hypothesis is faulty.

 

A sensor is quite unlikely to have enough of a load to generate ANY excess heat. Your diagnostic hypothesis is faulty.

We all seem to be in agreement.

 

I agree with the others it's not heat generated by the Hall sensor assuming that's what Cadillac is using. I'm sure there is some heat generated by the vehicle that might affect an aging sensor. Maybe it's the magnet that's causing the problem. Seems that in either case you would have to remove the drivetrain. I think your only hope is that it's an intermittent wiring problem as nsaspook mentioned, possibly a ground connection and that's assuming you can actually find it and work on it.

 

If it has three connections then it may be a hall sensor. If it has just two wires then it is probably a reluctance sensor.
One possible cause is 'rust jacking' where rust pushes the sensor outwards so increasing the distance between the sensor and the wheel it is sensing. I don't know whether this is a problem for this particular sensor.

 

The sensor in the post #3 link is a 2-wire type so, as noted above, isn't it more likely a reluctance sensor, not a Hall type?
Ferrous/ferric debris on the sensor could be a problem.

 

In any case, solving the issue requires pulling the Transmission.
( unless it's just a corroded Connector-Pin somewhere else in the Harness, which is not likely )
So, get used to the idea that it's going to be expensive, and/or, time-consuming.
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