Cleared my codes and rechecked them, throwing a 24, and a 51. I removed my AC system, would this cause the 24? dont know what would cause the 51. How do I fix these? And would either of them keep the car from starting? Anyone have a running car throwing these codes?
question about codes
- Thread starter LoveMy7MGTE
- Start date
24 is the air intake temp. signal and the 51 is the a/c switch or the neutral start switch. maybe your maf is bad?
As evil said, 24 is the AFM, specifically the Ks signal. 51 can be used to check the A/C signal for idle up or the NSW if you have an auto tranny (think of it as a diagnostic within a diagnositc) but it's almost always caused by no closure of the IDL contacts in the TPS. With T and E1 jumpered you should only get a gode 51 when the throttle is cracked. It should disappear when the trottle is closed. If you're getting code 51 all the time odds are you have no connection between IDL and E2 when the throtle is fully closed.
It's possible I put the TPS back together wrong when i reassebled it, or my throttle cable may be too tight. Ill check the cable and see if it goes away, then i pull the tps back out and check that. would a bad AFM keep the injectors from pulsing?jetjock said:
The TPS is nothing more than a potentiometer and a switch. The pot measures throttle plate angle while the switch tells the ecu the throttle is closed. It's importamt the ecu know when the throttle is closed as it uses the information for several things, most notably to turn on the ISC system. Equally important is the ecu know when the throttle is off-idle and that the TPS be "calibrated" to accurately reflect throttle plate angle.
It's the reason for all the monkey motion mentioned in the TRSM you need to go through when installing the TPS. Ohm it as per the manual. Be especially sure you have continuity between IDL and E2 when it's closed. You can also short these pins on the harness connector. If code 51 goes away the TPS is your problem. A bad AFM (code 24) will not prevent the injectors from firing. The car should start and idle but it won't run worth crap beyond that.
It's the reason for all the monkey motion mentioned in the TRSM you need to go through when installing the TPS. Ohm it as per the manual. Be especially sure you have continuity between IDL and E2 when it's closed. You can also short these pins on the harness connector. If code 51 goes away the TPS is your problem. A bad AFM (code 24) will not prevent the injectors from firing. The car should start and idle but it won't run worth crap beyond that.
LoveMy7MGTE said:
What Nick said. A lot of people seem to forget the TCCS will still run with bad sensors. It may not run well but it will run. This is designed into it so that a failed sensor won't strand you. I'm only talking about feedback sensors like coolant temp, AFM, O2, IDL contacts, ect..
Something like the CPS is a different matter and isn't considered a sensor. It's a core part of the engine management system and provides a "heartbeat" for the ecu. Without it you'll be dead in the water from both an injection and ignition standpoint..
thats the thing, my cps is fine, was taken from a running car, and I have spark, but no ijector pulse. oh, and i dicconected my throttle cable to make sure it wasnt overtensioned causing the code 51, cleared codes and the 51 is still there.jetjock said:
I have been working on an 89 N/A recently and noticed that it throughs a code 51 if the A/C is not on or when the A/C Clutch shuts off. Code 51 does say "No A/C signal" as well as No IDL. If you removed your A/C you probably need to figure how to fake out the ECU with a 12 volt jumper. Maybe somebody else can help that has done that.
Last edited:
LoveMy7MGTE said:
I seem to be constantly repeating myself on these idle and TPS issues over several posts. Did you do as I suggest? Did you check the TPS with a meter or short the pins on the harness and see if the code disappears? Your lack of injection is a separate issue. Weren't you the guy who was having Dr Jonez come over for a look see or am I confusing you with someone else? Is your AC turned off when you're doing this?
Jab89: Yep, a code 51 can be set by other than the IDL contacts but that'll only happen during a diag check and only occur when the AC is *on*, not off. It's simply a way to check the AC amplifier circuit without adding more codes.
Lets look at it from an electronic standpoint. The input in question is brought to ground (E2) when the IDL contacts are closed. When the contacts are open the input is "pulled up" to 5 volts by an internal resistor in the ecu. In fact all the inputs are either pulled up or down so they can't "float" when open. It's standard practice, any electronics guys out there will understand what I'm talking about.
The AC switch is not connected to the IDL input. It *is* connected to another input on the ecu however and is used to increase idle speed during AC operation. Since that input is also pulled up there should be no need to fool it when the A/C system is removed. That said, if LoveMy7M is checking codes and has the AC turned on he'll get code 51 even with the throttle closed. I sure hope that's not what we're looking at here. It'll also happen if if there is a problem in the neutral start switch circuit on an auto tranny car.