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Error Code 51, Troubleshooting & Repair for 1988 Pathfinder


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My 1988 Nissan Pathfinder is in fail-safe system operation and stutters when rpms rise above 2,800. The ECU's self diagnostic systems displays code no. 51 (Injector). I tested the 15-pin ECU connector and I have no voltage between terminals 101 & 102 and 114 shows voltage of -00.1?? and terminals 103 and 104 both show 12.85 voltage (good). This appears to indicate that one of the injectors is definitely bad.? Can anyone confirm this? If one injector is bad then no further troubleshooting is required as I plan to replace both injectors in that case.

 

Which brings brings me to my next question. I would like to do this repair myself but I am novice mechanic and not sure I can do it myself after reading the replacement instructions online. But I am in a bit of bind here because no repair shop I have called in my area will touch it. They all say it's too old.

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Generally you test injectors for resistance, not voltage. If your meter shows no continuity between the injector pins, either the injector itself is bad or there's a break in the wiring between the injector and the computer. If you do have continuity, compare the resistance against what's spec'd in the manual.

 

If that doesn't make sense, let me know and I'll pull out my '89 manual and see what I can work out. I haven't stared too much at the TBI troubleshooting because I don't have one, but the FSM's usually pretty good about laying out how to test stuff like this.

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Some places can test the actual injectors. Although those places tend to be dyno oriented bro . Might have a hard time finding one if your not near a big city

Sent from my Z982 using Tapatalk

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Best option with the throttle body injection system in those old trucks is to replace the entire throttle body assembly with a quality unit. It is pricey, but in the longer run, the better option. 

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I see that I need to test the resistance between the W/L connector and the ECU. Can someone please look at the attached image and tell me if that is the W/L connector? Also, where is the safety relay? I can't find it. Thanks for everyone's suggestions/help on this. I sure hope this doesn't end up being an expensive repair I can't afford. I really like my pathfinder and just want to get her running right again.

wl_connector2.jpg

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