Have an 87 mustang GT. Automatic. Will an A9L work when doing a MAF conversion?? I cannot find an A9P.
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- Thread starter NCsProdigy 87GT
- Start date
mikestang63
SN Certified Technician
yes. you can use an A9L in an auto, but not an A9P in a stick. You may encounter some surging idle when pushing in the clutch as the A9P has some difference for the torque converter.
Try reversing that answer...
The A9L is for 5 speed MAF and the Neutral Safety Switch circuit insures that there is a ground when the gear shift is in neutral. It works in conjunction with the 5 speed O2 sensor harness to make sure there is a ground when the gear shift is in neutral.
The A9P is for auto trans cars with a MAF, but it will work for 5 speed cars with some limitations. I have personally done this on two different 89 Mustangs. The Neutral Safety Switch in auto trans cars works with the auto transmission O2 sensor harness to make sure that there is 12 volts on the NSS circuit when the engine is cranked.
What the NSS (Neutral Safety Switch) does:
5 speed transmission: It has no connection with the starter, and the engine can be cranked without it being connected.
Auto transmission: It is the safety interlock that prevents the starter from cranking the engine with the transmission in gear.
What it does for both 5 speed and auto transmission cars:
The computer wants to make sure the A/C is off due to the added load on the engine for the engine running computer diagnostic tests. It also checks to see that the transmission is in Neutral (5 speed and auto transmission) and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.
The short answer to your question is to use an A9P with your auto trans cars unless you want to burn the signal ground trace off of the computer PC board.
Computer pins 40 & 60 are the computer power ground, which is the one of the most important grounds in an EFI car.
As soon as you enter into the thread with diagrams like above, it automatically becomes tech.Try reversing that answer...
The A9L is for 5 speed MAF and the Neutral Safety Switch circuit insures that there is a ground when the gear shift is in neutral. It works in conjunction with the 5 speed O2 sensor harness to make sure there is a ground when the gear shift is in neutral.
The A9P is for auto trans cars with a MAF, but it will work for 5 speed cars with some limitations. I have personally done this on two different 89 Mustangs. The Neutral Safety Switch in auto trans cars works with the auto transmission O2 sensor harness to make sure that there is 12 volts on the NSS circuit when the engine is cranked.
What the NSS (Neutral Safety Switch) does:
5 speed transmission: It has no connection with the starter, and the engine can be cranked without it being connected.
Auto transmission: It is the safety interlock that prevents the starter from cranking the engine with the transmission in gear.
What it does for both 5 speed and auto transmission cars:
The computer wants to make sure the A/C is off due to the added load on the engine for the engine running computer diagnostic tests. It also checks to see that the transmission is in Neutral (5 speed and auto transmission) and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.
The short answer to your question is to use an A9P with your auto trans cars unless you want to burn the signal ground trace off of the computer PC board.
Computer pins 40 & 60 are the computer power ground, which is the one of the most important grounds in an EFI car.
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