And Never EVER Feed Them After Midnight.....
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Melting Slicks
Joined: Jan 2002
Posts: 3,293
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From: Jackson MI
And Never EVER Feed Them After Midnight.....
I've got gremlins! Electric gremlins that is. My IAT sensor went to 5V about a week ago and I kept driving it since I didn't have time to fix it and it was only adding extra fuel and didn't hurt too much. I actually pulled the connector and I read 5V in both sides of the connector(harness side) so there's a short in the system somewhere.
So now it wouldn't start today as I went to leave work today. My ECT sensor is now also stuck at a high voltage. Are these two related? Is there a ground wire I need to clean and fix or is this just a weird coincidnence and I should just rewire both sensors and hope it doesn't happen again??
I'm running an Accel Gen 7 DFI so when they get stuck high it defaults to -40* for the IAT and 50* for the ECT. Which dumps a bunch more fuel into the car and makes it very hard to start, luckily the air temps cooled off enough tonight to let me get it started and get the thing home.
So now it wouldn't start today as I went to leave work today. My ECT sensor is now also stuck at a high voltage. Are these two related? Is there a ground wire I need to clean and fix or is this just a weird coincidnence and I should just rewire both sensors and hope it doesn't happen again??
I'm running an Accel Gen 7 DFI so when they get stuck high it defaults to -40* for the IAT and 50* for the ECT. Which dumps a bunch more fuel into the car and makes it very hard to start, luckily the air temps cooled off enough tonight to let me get it started and get the thing home.
I havent seen thr movie in a while though, I may be wrong.
Safety Car
Joined: Jun 2006
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From: FL
I just took a quick glance at my 93 FSM and don't see any common wiring but with 5 volts on both wires a bad ground is more likely than a short which should give you zero volts. The main ECM ground is near the oil filter, left side rear of engine, there may be others, best of luck.
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Now that I'm thinking about it doesn't the wiring go something like this...
+5V --- Wire 1 --- Sensor --- Wire 2 --- ECM Read --- Ground
If I disconnect the sensor and read the voltage at Wire 2 on the sensor side it should read 0V if everything is working properly. But even with a bad ground it should be a floating voltage, but still not exactly 5V (actually 4.x v). Wouldn't there have to be a short to the 5V supply somewhere? I'm going to check the ground wires anyways and see if that helps, it may just be that Saturn's moons areinline with something.
+5V --- Wire 1 --- Sensor --- Wire 2 --- ECM Read --- Ground
If I disconnect the sensor and read the voltage at Wire 2 on the sensor side it should read 0V if everything is working properly. But even with a bad ground it should be a floating voltage, but still not exactly 5V (actually 4.x v). Wouldn't there have to be a short to the 5V supply somewhere? I'm going to check the ground wires anyways and see if that helps, it may just be that Saturn's moons areinline with something.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
That sounds correct to me mn vette, but I'm not sure what happens if the ECM has a bad ground. Your short to 5 volt theory means both sensor return wires need to be shorted to 5 volts. Seems unlikely but suppose anything is possible, please post your solution when you find it. Good luck.
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Ok, here's the new revised theory
+5V --- ECM Read --- Wire 1 --- Sensor --- Wire 2 --- Ground
All that was wrong with my ECT sensor was that it was unplugged, but the ecm still read 5V. So I'm guessing the ecm read is just a current read that converts to a voltage.
As for the IAT, I ended up taking the ecm out and looking at the connections there, but I didn't see any problems and then I took the voltage readings at the plug and they seemed normal, 5V and 0V. So I tried an extra sensor I had lying around and it worked just fine. But I SWEAR I checked the voltage at the plug before and it was 5V on both sides. I guess all that matters now is that things are fixed and I can get some stress relief with some quick 0-60 runs.
+5V --- ECM Read --- Wire 1 --- Sensor --- Wire 2 --- Ground
All that was wrong with my ECT sensor was that it was unplugged, but the ecm still read 5V. So I'm guessing the ecm read is just a current read that converts to a voltage.
As for the IAT, I ended up taking the ecm out and looking at the connections there, but I didn't see any problems and then I took the voltage readings at the plug and they seemed normal, 5V and 0V. So I tried an extra sensor I had lying around and it worked just fine. But I SWEAR I checked the voltage at the plug before and it was 5V on both sides. I guess all that matters now is that things are fixed and I can get some stress relief with some quick 0-60 runs.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Originally Posted by mn_vette
Ok, here's the new revised theory
+5V --- ECM Read --- Wire 1 --- Sensor --- Wire 2 --- Ground
All that was wrong with my ECT sensor was that it was unplugged, but the ecm still read 5V. So I'm guessing the ecm read is just a current read that converts to a voltage.
As for the IAT, I ended up taking the ecm out and looking at the connections there, but I didn't see any problems and then I took the voltage readings at the plug and they seemed normal, 5V and 0V. So I tried an extra sensor I had lying around and it worked just fine. But I SWEAR I checked the voltage at the plug before and it was 5V on both sides. I guess all that matters now is that things are fixed and I can get some stress relief with some quick 0-60 runs.
+5V --- ECM Read --- Wire 1 --- Sensor --- Wire 2 --- Ground
All that was wrong with my ECT sensor was that it was unplugged, but the ecm still read 5V. So I'm guessing the ecm read is just a current read that converts to a voltage.
As for the IAT, I ended up taking the ecm out and looking at the connections there, but I didn't see any problems and then I took the voltage readings at the plug and they seemed normal, 5V and 0V. So I tried an extra sensor I had lying around and it worked just fine. But I SWEAR I checked the voltage at the plug before and it was 5V on both sides. I guess all that matters now is that things are fixed and I can get some stress relief with some quick 0-60 runs.
