sgauvry Posted December 9, 2017 Share Posted December 9, 2017 Gents and Ladies - I am looking for a complete engine compartment wiring harness for my 85 EFI truck. Purchasing a junk yard harness (if one could even be found) kind of defeats the purpose as I am already dealing with an original harness with many breaks in the lines. The point is that I'd like to purchase a newly created harness that is built to work with my EFI with a MAP sensor. There are harnesses available for a MAF sensor, but I cannot find any that incorporate the MAP. Any recommendations as to where to find such a harness are welcome. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 9, 2017 Share Posted December 9, 2017 The others will know for sure, but I'm pretty sure that the ones that use a mass airflow (MAF) sensor also use a manifold absolute pressure (MAP) sensor. Yours will be an EEC-IV system and according to the new book I have it does use the MAP but not the MAF, which was added with the EEC-V. The years for that varied by the vehicle and its delivery point, but all light trucks (under 8600 lbs GVWR) went to that by 1996. Bill will be able to answer the question definitively, but I think you can use a harness that has the MAF by removing the extra wires and re-pinning to your ECU connector as the -IV has a smaller connector than the -V. Link to comment Share on other sites More sharing options...
85lebaront2 Posted December 9, 2017 Share Posted December 9, 2017 The others will know for sure, but I'm pretty sure that the ones that use a mass airflow (MAF) sensor also use a manifold absolute pressure (MAP) sensor. Yours will be an EEC-IV system and according to the new book I have it does use the MAP but not the MAF, which was added with the EEC-V. The years for that varied by the vehicle and its delivery point, but all light trucks (under 8600 lbs GVWR) went to that by 1996. Bill will be able to answer the question definitively, but I think you can use a harness that has the MAF by removing the extra wires and re-pinning to your ECU connector as the -IV has a smaller connector than the -V. First item, 1985.5 and 1986 5.0L EFI systems are all by themselves, Matt went through that with his 1986. Everything changed in 1987 when EFI became standard on all but the 351 HO and 460 engines. MAF/SEFI started on the 5.0L in 1994 and was still using the EEC-IV system, 1996 was the year for the EEC-V introduction. That being said, there are a number of sources for an MAF/SEFI for the 5.0L engines, 1985 does not use an electronic transmission so any system for a Mustang update will work, but, you will have some interesting issues. (a) air filter location is unique to those years (b) EEC location is also unique to those years along with the power and fuel pump relays © harness routing is unique also, it passes through the firewall in an oval grommet near the throttle cable(d) EGR control system is unique to those years, but some cars used the same system (e) O2 sensor is a 1 wire in the back of the right exhaust manifold, I believe most of the MAF conversions use 2, one in each exhaust pipe, later trucks have it right where the two pipes come together and it is 3 or 4 wires due to the heater. MAF and MAP sensors are completely different circuits, MAP sensor uses the regulated 5 volt sensor and ground circuits and provides a peculiar to Ford high frequency signal that reflects the intake vacuum level (actually measures the Manifold Absolute Pressure in relation to normal air pressure), MAF sensors use the 12V EFI system power and the system ground and then a 2 wire sensor signal connected to the EEC. Good items, all the sensors are compatible with later computers and the Thermactor solenoids are the same. If you elect to stay with a MAP sensor system, you will need a later sensor. MAF truck air filter units can be found at junkyards along with a mounting bracket. there is a company, fiveology I believe sells a nice kit and does support trucks. Good luck with it! Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 9, 2017 Share Posted December 9, 2017 First item, 1985.5 and 1986 5.0L EFI systems are all by themselves, Matt went through that with his 1986. Everything changed in 1987 when EFI became standard on all but the 351 HO and 460 engines. MAF/SEFI started on the 5.0L in 1994 and was still using the EEC-IV system, 1996 was the year for the EEC-V introduction. That being said, there are a number of sources for an MAF/SEFI for the 5.0L engines, 1985 does not use an electronic transmission so any system for a Mustang update will work, but, you will have some interesting issues. (a) air filter location is unique to those years (b) EEC location is also unique to those years along with the power and fuel pump relays © harness routing is unique also, it passes through the firewall in an oval grommet near the throttle cable(d) EGR control system is unique to those years, but some cars used the same system (e) O2 sensor is a 1 wire in the back of the right exhaust manifold, I believe most of the MAF conversions use 2, one in each exhaust pipe, later trucks have it right where the two pipes come together and it is 3 or 4 wires due to the heater. MAF and MAP sensors are completely different circuits, MAP sensor uses the regulated 5 volt sensor and ground circuits and provides a peculiar to Ford high frequency signal that reflects the intake vacuum level (actually measures the Manifold Absolute Pressure in relation to normal air pressure), MAF sensors use the 12V EFI system power and the system ground and then a 2 wire sensor signal connected to the EEC. Good items, all the sensors are compatible with later computers and the Thermactor solenoids are the same. If you elect to stay with a MAP sensor system, you will need a later sensor. MAF truck air filter units can be found at junkyards along with a mounting bracket. there is a company, fiveology I believe sells a nice kit and does support trucks. Good luck with it! Bill - Perhaps I misunderstood, but I thought he just wanted a new wiring harness and didn't want to change to a MAF system. If that is true, then is there a harness that would work? Link to comment Share on other sites More sharing options...
sgauvry Posted December 9, 2017 Author Share Posted December 9, 2017 First item, 1985.5 and 1986 5.0L EFI systems are all by themselves, Matt went through that with his 1986. Everything changed in 1987 when EFI became standard on all but the 351 HO and 460 engines. MAF/SEFI started on the 5.0L in 1994 and was still using the EEC-IV system, 1996 was the year for the EEC-V introduction. That being said, there are a number of sources for an MAF/SEFI for the 5.0L engines, 1985 does not use an electronic transmission so any system for a Mustang update will work, but, you will have some interesting issues. (a) air filter location is unique to those years (b) EEC location is also unique to those years along with the power and fuel pump relays © harness routing is unique also, it passes through the firewall in an oval grommet near the throttle cable(d) EGR control system is unique to those years, but some cars used the same system (e) O2 sensor is a 1 wire in the back of the right exhaust manifold, I believe most of the MAF conversions use 2, one in each exhaust pipe, later trucks have it right where the two pipes come together and it is 3 or 4 wires due to the heater. MAF and MAP sensors are completely different circuits, MAP sensor uses the regulated 5 volt sensor and ground circuits and provides a peculiar to Ford high frequency signal that reflects the intake vacuum level (actually measures the Manifold Absolute Pressure in relation to normal air pressure), MAF sensors use the 12V EFI system power and the system ground and then a 2 wire sensor signal connected to the EEC. Good items, all the sensors are compatible with later computers and the Thermactor solenoids are the same. If you elect to stay with a MAP sensor system, you will need a later sensor. MAF truck air filter units can be found at junkyards along with a mounting bracket. there is a company, fiveology I believe sells a nice kit and does support trucks. Good luck with it! I appreciate this info and it does give me pause for thought. Not sure I want to convert to an MAF system, as Gary states in a related response. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 9, 2017 Share Posted December 9, 2017 I appreciate this info and it does give me pause for thought. Not sure I want to convert to an MAF system, as Gary states in a related response. Maybe you should clarify what the problem is and what your plans are? Link to comment Share on other sites More sharing options...
sgauvry Posted December 9, 2017 Author Share Posted December 9, 2017 Maybe you should clarify what the problem is and what your plans are? Thanks, Gary. As far as plans go, there's a tremendous amount for me to do. But, the focus now is on replacing the harness. I found this. It looks identical to my present harness except mine is equipped for the MAP sensor, whereas this one is equipped for a MAF sensor. Painless Performance Fuel Injection Harnesses 60511: https://www.summitracing.com/int/parts/prf-60511 Do you think I could make this work? Link to comment Share on other sites More sharing options...
85lebaront2 Posted December 9, 2017 Share Posted December 9, 2017 Thanks, Gary. As far as plans go, there's a tremendous amount for me to do. But, the focus now is on replacing the harness. I found this. It looks identical to my present harness except mine is equipped for the MAP sensor, whereas this one is equipped for a MAF sensor. Painless Performance Fuel Injection Harnesses 60511: https://www.summitracing.com/int/parts/prf-60511 Do you think I could make this work? The problem as I pointed out is the difference in the connections for MAP system and MAF systems. I do not think you will be able to find a new MAP sensor harness anywhere. The later MAP sensor harnesses from the factory are much netter than the 1985.5-1986 ones. I pulled 3 trying to get my son a good one. We finally took the best parts of the 4 (3 I pulled and the original) and made one near perfect harness. To my knowledge the truck, now in Chesapeake VA, still runs fine. If you are having problems, check where the harness ground connects at the battery negative post, there is a pigtail with a double pin connector, it is maybe 8" long and corrodes to where you either lose the ground or it is so high resistance it doesn't work right. Other common problem, the throttle position sensor, non-Motorcraft ones do not work right, Link to comment Share on other sites More sharing options...
PetesPonies Posted December 9, 2017 Share Posted December 9, 2017 The problem as I pointed out is the difference in the connections for MAP system and MAF systems. I do not think you will be able to find a new MAP sensor harness anywhere. The later MAP sensor harnesses from the factory are much netter than the 1985.5-1986 ones. I pulled 3 trying to get my son a good one. We finally took the best parts of the 4 (3 I pulled and the original) and made one near perfect harness. To my knowledge the truck, now in Chesapeake VA, still runs fine. If you are having problems, check where the harness ground connects at the battery negative post, there is a pigtail with a double pin connector, it is maybe 8" long and corrodes to where you either lose the ground or it is so high resistance it doesn't work right. Other common problem, the throttle position sensor, non-Motorcraft ones do not work right, I don't think too much of the aftermarket harnesses, no matter who's it is. I would, in your case, repair my original harness. Some soldering and shrink tube will fix about anything. Link to comment Share on other sites More sharing options...
sgauvry Posted December 9, 2017 Author Share Posted December 9, 2017 The problem as I pointed out is the difference in the connections for MAP system and MAF systems. I do not think you will be able to find a new MAP sensor harness anywhere. The later MAP sensor harnesses from the factory are much netter than the 1985.5-1986 ones. I pulled 3 trying to get my son a good one. We finally took the best parts of the 4 (3 I pulled and the original) and made one near perfect harness. To my knowledge the truck, now in Chesapeake VA, still runs fine. If you are having problems, check where the harness ground connects at the battery negative post, there is a pigtail with a double pin connector, it is maybe 8" long and corrodes to where you either lose the ground or it is so high resistance it doesn't work right. Other common problem, the throttle position sensor, non-Motorcraft ones do not work right, "If you are having problems, check where the harness ground connects at the battery negative post, there is a pigtail with a double pin connector, it is maybe 8" long and corrodes to where you either lose the ground or it is so high resistance it doesn't work right. Other common problem, the throttle position sensor, non-Motorcraft ones do not work right," I replaced that about two years ago, at the recommendation of Vinny. Anyway, I want a new harness for the fact that if I indeed refurbish this vehicle, I want it done right before I present it to my boy. Link to comment Share on other sites More sharing options...
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