86F150CA Posted September 25, 2020 Share Posted September 25, 2020 I can't figure you how to remove the computer from my 1986 F150 4.9L. It is under the dash but I can't release it from the bracket. I need to test it as part of a No Spark problem. This is an EEC-IV system with California Emissions if that matters. Link to comment Share on other sites More sharing options...
Sac79 Posted September 25, 2020 Share Posted September 25, 2020 Everything was disassembled by the time I got to the computer and it was 5 years ago... But I know that the bracket has a bolt above the unit and one on the driver's side behind it, the top one going into the bulkhead and the side one into the vertical mounting plate. Neither I imagine would be easy to access with everything in place. My computer is still attached to the bracket and stored in a box somewhere, I don't know if there is an easier way to detach the computer from the bracket. Sorry, hopefully someone else has helpful advice. Link to comment Share on other sites More sharing options...
old55pete Posted September 25, 2020 Share Posted September 25, 2020 You may not need to remove the computer from the dash. When was the last time you changed the TFI module on the distrubiter? Have you checked the rotor and cap to make sure they are not damaged in any way? The reason I ask is the TFI module controls spark and they tend to over heat and fail. Link to comment Share on other sites More sharing options...
86F150CA Posted September 26, 2020 Author Share Posted September 26, 2020 You may not need to remove the computer from the dash. When was the last time you changed the TFI module on the distrubiter? Have you checked the rotor and cap to make sure they are not damaged in any way? The reason I ask is the TFI module controls spark and they tend to over heat and fail. The TFI would be my primary suspect except that I was checking the cable from the computer to the TFI and, with the ignition key in the Run position and cable to TFI disconnected, I measured 12 V from wire 4 (Run signal) to engine ground; and 7 V from wire 4 to wire 6 (signal ground). Also, I get 5V from wire 6 (signal ground) to engine ground. I can't find any wiring to the computer that might be disconnected/broken or shorted so I wanted to inspect the computer. I won't be surprised if the TFI module is bad but I want to eliminate the computer first. Link to comment Share on other sites More sharing options...
86F150CA Posted September 29, 2020 Author Share Posted September 29, 2020 The TFI would be my primary suspect except that I was checking the cable from the computer to the TFI and, with the ignition key in the Run position and cable to TFI disconnected, I measured 12 V from wire 4 (Run signal) to engine ground; and 7 V from wire 4 to wire 6 (signal ground). Also, I get 5V from wire 6 (signal ground) to engine ground. I can't find any wiring to the computer that might be disconnected/broken or shorted so I wanted to inspect the computer. I won't be surprised if the TFI module is bad but I want to eliminate the computer first. First prize goes to old55pete. I had a discarded TFI from my mechanic and installed it. Truck started in less than one revolution! It now has a new TFI module. Now I can get back to the original problem, failed Smog. It is still a mystery to me why the TFI failed so suddenly. Thanks to everyone. I will be back with more questions. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 29, 2020 Share Posted September 29, 2020 First prize goes to old55pete. I had a discarded TFI from my mechanic and installed it. Truck started in less than one revolution! It now has a new TFI module. Now I can get back to the original problem, failed Smog. It is still a mystery to me why the TFI failed so suddenly. Thanks to everyone. I will be back with more questions. Congrat's!!!! Link to comment Share on other sites More sharing options...
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