I am new to this forum and really need some guidance. I am fairly good with electrical, but some electronics stump me.
My problem is that I need to install a small op-amp into my car, '95 Cadillac Seville. The transmission has an "Input speed sensor" that sends an AC voltage
signal to the PCM for monitorning, etc. The output voltage from sensor must never go below 5VAC, or the "Check Engine" light will come on.
This is my problem, since the car is due for a smog check in a few weeks and will automatically fail with the "Check Engine" light on. The car
otherwise runs and shifts properly. I just cannot take it to the smog station until the "Check Engine" light turns off. The major problem is that the sensor is a "$20 part
buried $2,000 deep in labor in the transmission", otherwise I would replace it. Some guys say the sensor itslef is fine, and the age of the signal wire
has caused high resistance, lowering the voltage. Maybe a bypass wire?
The guys on the Cadillac forum stated that a few of them were able to "fool" the computer into seeing 6,7,8 VAC signal by using the simple LM741 op amp cirucit.
I have asked a number of them for help, but I have no responses. I have researched the amp on Google, and it seems easy enough to build on my garage
workbench. I just do not know how to install it. It looks like it has a "voltage in" and "voltage out" with some grounds. Do I just insert in inline on the output
signal wire, so only 2 or 3 volts goes into the amp and much more than the minimum 5 goes out, and do I have to ground the circuit board, etc?
Please, and assistance will be a great help. I really like the car, runs and looks great, I just have to pass smog !! THANKS !
My problem is that I need to install a small op-amp into my car, '95 Cadillac Seville. The transmission has an "Input speed sensor" that sends an AC voltage
signal to the PCM for monitorning, etc. The output voltage from sensor must never go below 5VAC, or the "Check Engine" light will come on.
This is my problem, since the car is due for a smog check in a few weeks and will automatically fail with the "Check Engine" light on. The car
otherwise runs and shifts properly. I just cannot take it to the smog station until the "Check Engine" light turns off. The major problem is that the sensor is a "$20 part
buried $2,000 deep in labor in the transmission", otherwise I would replace it. Some guys say the sensor itslef is fine, and the age of the signal wire
has caused high resistance, lowering the voltage. Maybe a bypass wire?
The guys on the Cadillac forum stated that a few of them were able to "fool" the computer into seeing 6,7,8 VAC signal by using the simple LM741 op amp cirucit.
I have asked a number of them for help, but I have no responses. I have researched the amp on Google, and it seems easy enough to build on my garage
workbench. I just do not know how to install it. It looks like it has a "voltage in" and "voltage out" with some grounds. Do I just insert in inline on the output
signal wire, so only 2 or 3 volts goes into the amp and much more than the minimum 5 goes out, and do I have to ground the circuit board, etc?
Please, and assistance will be a great help. I really like the car, runs and looks great, I just have to pass smog !! THANKS !