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International Automotive Technicians Network
2003 Infinity - C1142
Posted to Technical Tips Forum on 3/26/2019 13 Replies

SI (factory flowchart viewed via All-Data) is wrong/incomplete on the above tagged vehicle. (2003 Infiniti FX45 for you app folks)

SI says C1142 is Brake Fluid Pressure Sensor Circuit and the troubleshooting is to check the wires and connectors, then replace the sensor (basically, that is really all it says). Since the sensor was soaking wet with fluid, that seemed like a good idea. But of course, it wasn't fixed. The data list and a lab scope showed the sensor working fine, so a false DTC and therefore an ABS module seemed to be in my future.

But that little voice in the back of my head said, "I bet there is something else that can cause this issue".

Well, as the saying goes, it's not WHAT you know, but WHO you know, so I asked fellow member Matt Hutchens (who has spent most of his life on Asian cars in Japan) and fellow member (and Nissan tech) Bryan Lehman.

Both mentioned the Stop/Brake Lamp Switch. If you look at the wiring diagram, that is not even an input to the ABS. However the info is communicated through the network. So, basically, if the ABS module sees pressure, but no pedal-push, it figures the pressure sensor is bad.

So I checked for brake lights. None. I looked for the fuse. None. Some of you can guess where this going now. Yes.....The "button" on the brake pedal that holds the brake light switch closed was missing too. The button for the cruise control cancel switch was even gone. Sheesh.

So anyway, because some "entrepreneur" pulled the STOP fuse before the car ever got here, and the SI is incomplete, we almost sold an unnecessary ABS module that still would not have fixed the car.

ps, original complaint was "warning lights in dash". The VDC OFF and SLIP were the two mil that led me to scan the ABS.

Geoff from Hawaii

13 Replies Received (View Replies)

 

car Vehicle Data

2003 Infiniti FX45 4.5L

Engine4.5 L
Trans5-speed Automatic (Electronic)

car Vehicle Data

2003 Infiniti FX45 4.5L

Engine4.5 L
Trans5-speed Automatic (Electronic)