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CarDoc, Independent European Shop owner
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Experience:  20 years of experience working with European cars. Independent European shop owner and technician.
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I have a p1590 code on my 2003 land rover, and cant find what

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I have a p1590 code on my 2003 land rover, and cant find what that is anywhere. do you know?
Hello, I'm Jason.
I will do my best to answer your question quickly and accurately using the information you have provided.

Typically, this is due to a faulty ABS control module. I'll post the rest of the code information below.

Rough Road Signal Description
The SLABS/ABS control module transmits a PWM signal indicating rough road for misfire detection disablement.
The ECM has input diagnostics for this signal.

There are three plausibility checks of the PWM signal during which a fault is detected if:
The PWM signal is greater than a threshold indicating an electrical short to battery positive.
The PWM signal is less than a threshold indicating an electrical short to ground.
The PWM signal is greater than 44.92 % but less than 55.08 % indicating an error with the SLABS/ABS control module.

DTC P1590
Rough road signal implausible Drive cycle A:Signal implausible.

Possible causes by suggested order of priority:
Connectors C504, ECM C637 (B).
Open circuit - C637/34 (RG) to C504/4 (RG).
ABS fault.
Connectors C504, ECM C637 (B).
Check for connector not correctly latched, backed out pins, damaged pins, corroded pins.
Open Circuit - C637/34 (RG) to C504/4 (RG).
Check resistance > 1M Ohm
ABS Fault.
Carry out diagnostic checks on the ABS system. POSSIBLE FAULTS
Faulty ABS ECU or wiring.
Customer: replied 3 years ago.

could it be a bad positive battery terminal (coroded). because all my lights are on. ABS,tc,brake,and down hill lights.

Extremely unlikely that a corroded terminal would cause that, unless it's causing an extreme low voltage signal to the ABS computer. If the car is starting, then this is not the cause.

Also, with regards XXXXX XXXXX other lights on, that's normal. If there is any fault at all with the ABS system, all of the others are affected, as they require information from the wheel speed sensors, and ABS computer to function correctly.
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