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analog voltage channels going crazy


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Hey guys I'm just trying to get my g4+ set up on my Evo 5 and I'm running into weird problems with the voltage analog signals. First I get a code 74 for 5v supply error, and with that I also get code 14 and 20 (meaning voltage signal below the set limit) and codes 43 and 16 (meaning voltage above the limit). I checked the limits and they all seem normal, but what's happening is when I turn the key on the voltage on the analog channels fluctuates faster then you can even see. I'm pretty much a noob at all of this and trying to learn as I go but I'm getting an etune so I have to figure out the set up aspect of it on my own pretty much. thanks for any help in advance

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The 5V out error is the pointer this is currently sitting at 2.06V and the internal 12V is also low at 10.68V this would indicate an excessive load on the 5V out.

This is located on pin 81 of the ECU can you disconnect pin 81 from the plug and then check the 5V supply reading.

 

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Yeah I just checked it and I'm only getting 1.7 volts 

 

You need to disconnect or snip that wire, if the ECU 5V output then recovers after disconnecting then that means something connected to that wire that is "shorting" to ground.  

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Ok. so embarrassingly enough I found the one short which turns out I had my map sensor plugged in upside down....I know I know....but now I still have an issue. The MAP sensor and inlet temp sensor are working properly, however the TPS and coolant temp sensor are continuously getting more then the 5v maximum. When I checked the coolant temp sensor it was getting 8.4 volts. Any idea why this would be?

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Yes the 5v says 5.02 on pc link. I guess there must be a short somewhere but that doesn't make much sense to me considering this car was running on a haltech ps1000 before and I didn't change any wiring on either of those sensors to switch over to the Link

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There are only 1 or 2x 5v reference outputs on the link though, which means you more than likely split it into 5 or 6 wires to feed all the 5v sensors. Anywhere you ran a wire that takes 5v can potentially short onto a 12v wire, and once that 12v gets onto the wire, it "flows" out to every sensor fed by the same "5v" wire. Have a look at anywhere you've wired in a 5v sensor for a start. I'd guess that somewhere you've connected a 5v ref line to an existing wire that feeds a sensor, but that wire was already getting 12v fed to it by another source. Could also be that you've run a 5v wire to a sensor thinking you're powering it, when its acutally powered by 12 on another pin already, and so power is now running through the sensor from 12v to 5v.

If that fails, unplug every single connector on the engine but leave the ECU connected, power up and check for 5v on that MAP pin again, this tells you if its a badly wired sensor of a loom issue. If its still 8.4V, unplug the ECU connector, and any link>chassis connectors so you have the engine harness completely unplugged. Then test for continuity between the 5v ref pin/pins on the link connector, and every wire in every plug on the engine harness. you should only find continuity to 1 pin on each of the 5v sensors, and if you find continuity to *anything* else, that wire is somehow bridging onto the 5v pin. If you put together a list of which wires 5v is "leaking" onto, hopefully it can be used to track down where in your loom you have a short between a 5v wire and probably a 12v wire, and worst case, you pull your loom apart and physically follow the problem wires looking for connections to incorrect things.

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ok I found the ground problem, Those two sensors weren't grounded to the sensor ground pin, but now everythings fixed and operating properly. Im left with another weird issue though. This was going on before but I thought I'd deal with it later. Whenever I turn the key to the on position the Rad fans turn on. On runtime values all the engine fans say they're off, and I've tried configuring them on both options for auxiliary output. (evo 5 and evo 8 are different) but nothing seems change these fans. any suggestions?

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