Tachometer Acting Up and CEL 44

[Aikouka]

Yesterday, after driving the car and when I was about at my driveway, my CEL lit up and I turned into my driveway and went to pull into the garage. That's when the RPMs started to act VERY odd. The car was on, and I put it into neutral, and the RPMS were VERY erradic. They would go from almost 0 to about 1.5k and keep fluctuating. Then I turned the car off, started it again and then pressed on the gas a little bit. Everything sounded fine with the engine, but the RPMs stayed at 0. Once I put the car into 1st and pulled into the garage all the way, the RPMs were acting fine again.

I checked the error code this morning and I got error code 44 again. I had this error before right before I put my new stereo in, so I cleaned some ignition connectors and all seemed fine. Then tonight the same error code came back. If I had a working ohmmeter I would follow Haynes way of testing it, but the special batteries ( not AA or anything like that ) need to be replaced.

Could the problem be with my Crankshaft Position Sensor? Since it sends the RPM signal to the ECU, this was my first guess.

Thanks for any help or advice that you can give me.

 

[Aikouka]

Okay, I hooked up a multimeter with the car started and the key turned to ON and the multimeter was set to AC 20v. I got a reading of about 10.8v through the line (with the negative hooked directly to the battery.) Now, if I just do a little math here, and divide 10.8 by 12, I get .9. Then if I multiply that by 9 for how high the tach goes, I get 8.1. So I'm assuming that could be read as 810rpm (note that I can't remember the exact reading that I got, but it was in the 10s).

So does this mean that my electronics for the tach are working since I'm getting a signal from the tach connector? Could my ECU still be at fault, but the whole unit needs to be replaced, because there was a yellowish residue on the board?

EDIT: I played around with some negative connectors today (the one that connects to the intake manifold and then to the body right beside the cruise control box mainly) and I moved that one from the single "ledge" on the Intake Manifold where the wiring harness' ring holder is (it simply was too loose for my liking) so I moved it back to where it used to be on the 3rd ledge by the accelerator cable.

Then I turned the car on and the tach worked, I was quite happy. I came back inside and then went back outside to try to get pictures of what I did. To make sure I wasn't celebrating early, I started the car again and the tach was working ... but then it quit out again. So now the Tach is back to its previous habits of working half the time. It's strange how it worked better after I cleaned the one negative connector up, and put it on a spot that it could tighten well.

I'm thinking about going through and cleaning up all of the ground connections, and then trying it again.

 

[steve]

Okay, I hooked up a multimeter with the car started and the key turned to ON and the multimeter was set to AC 20v. I got a reading of about 10.8v through the line (with the negative hooked directly to the battery.) Now, if I just do a little math here, and divide 10.8 by 12, I get .9. Then if I multiply that by 9 for how high the tach goes, I get 8.1. So I'm assuming that could be read as 810rpm (note that I can't remember the exact reading that I got, but it was in the 10s).

So does this mean that my electronics for the tach are working since I'm getting a signal from the tach connector? Could my ECU still be at fault, but the whole unit needs to be replaced, because there was a yellowish residue on the board?

Interesting thought process. What you've missed is, that the tach signal isn't a analog signal but a digital one. It's a 12v pulse train that varies in frequency. You need an automotive meter with a tach setting, a multimeter with a frequency setting, or an oscilloscope to make sense of it.

Steve

 

[Aikouka]

Unfortunately, I don't have any of those to see if I'm getting the correct measurements.

But do you have any ideas of how playing with ground cables could make the tach work for a little bit. Because today the tach went back to it's behavior as of late and just stopped working once the car was started. I can't remember, but I think I also disconnected the negative cable at one point while toying with the ground cables and then I reconnected it when the tach started working.