David McNamara

Hey guys, long time lurker, first time poster. I have a 86 Maxima with just a hair over 120k miles on it that does not want to start anymore. The car has sat fro about 7-8 months since it stopped working because I havent had time to work on it but now I have some spare time and I would like to get back to troubleshooting this car and getting it back on the road. When I pulled the error codes from the ECU I am getting codes 23 and 45.

I believe 45 has to do with the fuel pump starting to go out on the car, and I have ordered a new one along with the entire in tank sending unit assembly. I plan on replacing the fuel filter at the same time just because I dont know when it was done last and its an extra $10.

Code 23 looks like it has to do with the TPS. Just wondering if this is correct and if there is any way to verify it is bad before I just order one.

Thanks in advance!
David M

aw11power

code 23 throws when the ecu logic sees a tps signal that doesnt jive with the current load/RPM condition. it wont cause a no-start. it can be verified. get a volt meter and connect black to battery ground with the key forward. back probe with red volt meter probe on middle wire of TPS connector with key forward. there should be 12 volts signal from the computer there. then back probe the top pin. should also be 12 volts but should lose 12 volts as soon as you partially open the throttle. the 3rd bottom pin should only have 12 volts when the throttle is ope. completely. this is by the book how you test the sensor. also, the sensor isnt usually bad. these harnesses are not well weather sealed. they tend to build corrosion on the pins in the connector. so unplug it amd look at the pins on the harness side. if they have blue/green crud, then youve found youre TPS problem. conector and sensor pins can be cleaned with a very small file and then you put dielectric grease in the connector and plug it back in. ive seen this on more old VG30s than i can count.

secondly....dont replace the fuel pump right away. the fuel pump code almost never comes on when the pump is "failing". the ECU monitors the electrical circuit only so it only throws that code if there is an open or short in the circuit. so before you replace pump, pull up the back seat and use a voltmeter to see if the pump is getting 12 volts for about 3 seconds after the key is turned(priming). if it is, its a bad pump. if it isnt, then check the fuel pump relay next. thats most likely youre no-start cause.

diagnostics must be carried out before repairs or you waste a lot of time and money. promise.

David McNamara

The the fuel pump was completely dead. Used a voltmeter and was getting 12v to the pump. I pulled it out and ran 12v to it and got no noise out of it at all. A new Bosch was only $99 for the entire assembly so no big deal. My fill arm was seized so its nice to be able to see fuel levels again.

Also RockAuto had a TPS for $23 shipped. Already ordered it and it arrived today. Swapped it in and the car started right up. Its running a little rough still, but i think with a new set of plugs and wires along with an oil change and new air filter it will be back on the road again.

Thanks for the reply