DieHarder
Senior Member
- Joined
- Nov 9, 2019
- Posts
- 1,467
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- 758
2006 Mustang - Funny....just dealt with this issue. Burnt up F3 (the 40 amp) and the fan switch/resistor due to a self-imposed "fix" because temps were too low. After tearing everything down, replacing the fuse and fan switch harness and performing continuity checks of the entire circuit including disassembling the BEC blocks couldn't find anything wrong and I mean nothing but the fan would still not come on... Long story short Lito provided a tune that turned the fans on at 20F. (Had to have some way of ensuring the ECU signal was actuating the relays). For whatever reason loading up that tune did the trick. Not sure if that was because the temps weren't getting high enough or the ECU wouldn't send the ground (command signal) to the relays but the fan would not turn on. Then reloaded the proper tune with correct ON/OFF settings and everything now works as it should.
Regarding the comment about moving the CHT sensor and plugging it into a radiator hose or similar location will negatively affect the PCM is inaccurate. That is exactly the setup DOB uses on their manifolds (mine is installed in the crossover underneath) and it works fine. Actually, doing so puts the sensor directly in the water stream and will give you the most accurate readings of water temps coming out the radiator (as long as you choose a location like the top hose or crossover before the thermostat).
Anyway, I agree with the gentlemen that most everyone with burnt up connectors are experiencing corrosion, grounding and resistance issues. Think about it, if those connectors are getting hot enough to melt then they're acting like resistors which dissipate heat. You don't want heat in connectors, you want good, clean connections, no resistance... My advice is clean up/wire brush those connections, clean off corrosion wherever you find it and use dielectric grease (some will push back against that but I find that it helps prevent future corrosion and doesn't affect the connection. However, if you don't need it then don't use it).
Additionally, clean up all of the grounds you can find. Especially main harness to body grounds. I had a situation where my alternator appeared not to charge and I have an expensive alternator that was thoroughly QC'd before I installed it. After 3 trips to the auto store who told me it was bad each time and even taking my car into a dealer/stealer who also told me the alternator was bad....it turns out my grounds were "floating" due to rust/corrosion. They appeared fine but in many cases the connections are going from steel to aluminum which immediately sets up a low current situation resulting in galvanic corrosion (dissimilar metals have issues connecting to one another). The short term fix for me was to run a new 4 gauge cable from the main ground on the passenger strut tower all the way to a bolt on the alternator body to ensure an accurate ground reference. Haven't had an issue since. And yes, I continue to clean grounds every chance I get.
Regarding the comment about moving the CHT sensor and plugging it into a radiator hose or similar location will negatively affect the PCM is inaccurate. That is exactly the setup DOB uses on their manifolds (mine is installed in the crossover underneath) and it works fine. Actually, doing so puts the sensor directly in the water stream and will give you the most accurate readings of water temps coming out the radiator (as long as you choose a location like the top hose or crossover before the thermostat).
Anyway, I agree with the gentlemen that most everyone with burnt up connectors are experiencing corrosion, grounding and resistance issues. Think about it, if those connectors are getting hot enough to melt then they're acting like resistors which dissipate heat. You don't want heat in connectors, you want good, clean connections, no resistance... My advice is clean up/wire brush those connections, clean off corrosion wherever you find it and use dielectric grease (some will push back against that but I find that it helps prevent future corrosion and doesn't affect the connection. However, if you don't need it then don't use it).
Additionally, clean up all of the grounds you can find. Especially main harness to body grounds. I had a situation where my alternator appeared not to charge and I have an expensive alternator that was thoroughly QC'd before I installed it. After 3 trips to the auto store who told me it was bad each time and even taking my car into a dealer/stealer who also told me the alternator was bad....it turns out my grounds were "floating" due to rust/corrosion. They appeared fine but in many cases the connections are going from steel to aluminum which immediately sets up a low current situation resulting in galvanic corrosion (dissimilar metals have issues connecting to one another). The short term fix for me was to run a new 4 gauge cable from the main ground on the passenger strut tower all the way to a bolt on the alternator body to ensure an accurate ground reference. Haven't had an issue since. And yes, I continue to clean grounds every chance I get.
