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Originally I was planning on just getting an AEM GPS speedometer, but I read in the manual on page 13A-119 that the ECU is using the speed signal to "perform idle speed control servo control." Sometimes my idle has been dropping low and now I think these two are related, so I think I actually need to fix this to solve both the problems.
I think you might be confusing two different issues. Only time ECU will use that speed signal for idle speed is when throttle close and vehicle coasting, so if idle is dropping low while coasting then this may be true. But if vehicle is stopped, then ECU uses engine rpm from crank sensor pulse to set IAC position. If idle is dropping low when stopped you may have an IAC problem.
 

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I think you might be confusing two different issues. Only time ECU will use that speed signal for idle speed is when throttle close and vehicle coasting, so if idle is dropping low while coasting then this may be true. But if vehicle is stopped, then ECU uses engine rpm from crank sensor pulse to set IAC position. If idle is dropping low when stopped you may have an IAC problem.
I did not know that. It is when the car is stopped.

That means I have two separate issues - 8.9 volts at speed sensor wire 3, and an issue with the crank sensor? Lovely...

Sorry MrLWRC for highjacking your thread...
 

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That means I have two separate issues - 8.9 volts at speed sensor wire 3, and an issue with the crank sensor? Lovely...
Not necessarily with crank sensor as that would cause engine performance issues also. As I said possible problem with IAC servo, concerning idle when stopped not with speedometer.
 

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Not necessarily with crank sensor as that would cause engine performance issues also. As I said possible problem with IAC servo, concerning idle when stopped not with speedometer.
Oooooohhhhh. That makes sense. IAC servo gets signal from speed sensor when slowing down, and from crank sensor when at a stop. I am not having engine performance issues (that I'm aware of). It isn't dropping a lot when coming to a stop, it's after a little while ~30 seconds while sitting at a stop. Thank you very much.
 

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Dude pull your cluster like I said. I'm willing to bet the capacitors on your speedo are bad. This is a quick and easy $5 fix if you can turn a screwdriver and know how to solder.
 

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I'm not sure if the latest speedo-pulling recommendation was targeted at me, but I pulled mine anyway and here are the pics.
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Yep it's bad just like mine was, but that's actually a resistor, it should match up with the little tan thing with the color stripes on it. The only odd thing is your resistor doesn't seem to match the one that was on my speedo, as you can see in the attached. The one on my board was a 4.7k Ohm 5%, the one on yours is showing 15K Ohm 5% unless the colors aren't showing right in the picture(I see Brown/Green/Orange/Gold). You can check it off this resistor calc tool here.

Either way you can get them for like 20 cents off digikey, and assuming you already have a soldering gun it is a simple 5 minute fix. I'd go ahead and replace the capacitors too while you were at it, because resistors don't usually go "bad" like capacitors do. The capacitors are 6.8uF 25V I believe, but it should be printed right on the side of them, so that's easy you check. Hell while you are at it, replace the tach capacitors too.
 

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Yep it's bad just like mine was, but that's actually a resistor, it should match up with the little tan thing with the color stripes on it. The only odd thing is your resistor doesn't seem to match the one that was on my speedo, as you can see in the attached. The one on my board was a 4.7k Ohm 5%, the one on yours is showing 15K Ohm 5% unless the colors aren't showing right in the picture(I see Brown/Green/Orange/Gold). You can check it off this resistor calc tool here.

Either way you can get them for like 20 cents off digikey, and assuming you already have a soldering gun it is a simple 5 minute fix. I'd go ahead and replace the capacitors too while you were at it, because resistors don't usually go "bad" like capacitors do. The capacitors are 6.8uF 25V I believe, but it should be printed right on the side of them, so that's easy you check. Hell while you are at it, replace the tach capacitors too.
Okay I'll give it a go. Thank you very much. I'm really hoping this will fix the broken speedo.
 

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So, I replaced the capacitor in the speedo and put it all in with no luck. I also replaced the idle control servo motor. The speedometer still isn't working. One weird thing is the trip meter seems to be spinning. Thoughts?
 

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So, I replaced the capacitor in the speedo and put it all in with no luck. I also replaced the idle control servo motor. The speedometer still isn't working. One weird thing is the trip meter seems to be spinning. Thoughts?
Did you replace that burned out resistor or just the caps? Also did you get the polarity right on the caps, they only go on one way(gotta make sure the stripe face the correct side) Also my speedo had gotten so bad that I basically had to reset the needle. Try putting the cluster in without the plastic cover, take the speedo needle off, turn the car on and then put the needle back on at a known speed like 60mph(use waze or something), and see if it works. The little coil that drives the needle might have come unwound as well, so you might need to put the needle on, spin it clockwise past the right stopper(by the 180mph mark or whatever it is) and back to rest on the 0mph stopper, if that makes sense. If your trip and regular odometer work when they didn't before it's a good sign at least, because I believe they are all driven by the same signal.
 

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Did you replace that burned out resistor or just the caps? Also did you get the polarity right on the caps, they only go on one way(gotta make sure the stripe face the correct side) Also my speedo had gotten so bad that I basically had to reset the needle. Try putting the cluster in without the plastic cover, take the speedo needle off, turn the car on and then put the needle back on at a known speed like 60mph(use waze or something), and see if it works. The little coil that drives the needle might have come unwound as well, so you might need to put the needle on, spin it clockwise past the right stopper(by the 180mph mark or whatever it is) and back to rest on the 0mph stopper, if that makes sense. If your trip and regular odometer work when they didn't before it's a good sign at least, because I believe they are all driven by the same signal.
I replaced the resistor and a cap next to it that was clearly burned. I was careful to put the cap in the right way.

I haven't yet tried resetting the needle, so that sounds like a good next step. Thank you.
 

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I tried resetting the needle. I drove a little further this time, and while my trip meter seemed to be spinning last time, it wasn't this time. I don't think I reset it correctly, because when I turned it back on, while it started off at 0, when I turned the car on it came up to ~25 and just stayed there. It looked like it wobbled a little but basically stayed around 25. When I turned it off again, it went back down to 0. I wish I had someone else's cluster and sensor to swap in and try.
 
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