What does the fault codes P1592 and P1667 say is the problem and what to repair?

U1900 FORD - CAN Communication Bus Fault

Read more: https://www.autocodes.com/u1900_ford.html
Possible causes
Faulty / intermittent ignition switch connections
CAN Bus wiring intermittently open/shorted to power or ground Faulty / intermittent connection at PCM
Faulty electrical connections at ABS Control Module
Faulty electrical connections at the instrument cluster
Poor connections at the trailer brake controller/trailer connector

Tech notes This is typically a false/intermittent code. It can occur if: Someone hooks up a scanner to the OBDII port while the ignition is on or while the engine is idling. A trailer brake system is installed improperly/incorrectly on a truck with ABS (anti-lock brakes).

When is the code detected? When the PCM, Brake Controller and Instrument Cluster are unable to communicate with each other at any time while the ignition switch is turned to the "Run" position, code U1900 sets in memory.

Possible symptoms Engine Light ON (or Service Engine Soon Warning Light) Amber ABS (Anti-lock Brakes) Light ON Wrench Light On

U1900 Ford Description The Anti-ock Brakes System (ABS) module, the Powertrain Control Module (PCM), and the instrument cluster communicate over the Controller Area Network (CAN) Bus. This is a high-speed bus communication system and is not fault tolerant, which means any type of intermittent/loose connection between these 3 controllers will cause communication to stop. When the PCM, ABS module and instrument cluster are unable to communicate with each other at any time while the ignition switch is turned on, code U1900 will set.

Read more: https://www.autocodes.com/u1900_ford.html

When the ABS warning (or any other for that matter) comes on a fault code is set in the computer control module, to start diagnosis and testing you need to have that fault code, that requires the ABS system be scanned for fault codes. Right now the ABS system has been disabled until the problem is repaired.

Here's a link to your P1592 CODE AND REASON'S. 2003 Land Rover Discovery Codes Computer Problem 2003 Land Rover

If those lights are on, then there are codes. Not engine codes, but ABS codes. If by chance there aren't ABS codes, then you have a data wire problem or the instrument panel is bad.

PRE-DIAGNOSTIC INSPECTIONBefore diagnosing ABS/TCS, perform a comprehensive visual inspection of system as follows.Check ABS/TCS wiring harness connectors for looseness. Check harness routing; pay particular attention to wheel speed sensor wiring harness routing. Check fuses No. 1D, 5B and 6B in instrument panel fuse block. Check fuses No. 1 and 2 in underhood fuse block. Check brake fluid level in master cylinder reservoir. Check brake fluid level in Pressure Modulator Valve (PMV) assembly reservoir. Ensure parking brake is fully released. Ensure parking brake switch is functioning properly. Always perform ABS/TCS system functional check before using DIAGNOSTIC CODE CHARTSThe EBCM/EBTCM has self-diagnostic capability, which can detect system failures. Fault codes stored by EBCM/EBTCM can be displayed using Tech 1 scan tester. There are no provisions for flash code diagnostics.Begin ABS/TCS diagnosis with PRE-DIAGNOSTIC INSPECTION procedure. If failures are found during pre-diagnostic inspection, perform necessary repairs, and proceed with ABS/TCS FUNCTIONAL CHECK. See Fig. 5 .If no failures are found during pre-diagnostic inspection, go to ABS/TCS FUNCTIONAL CHECK. See Fig. 5 . The ABS/TCS FUNCTIONAL CHECK will either indicate ABS/TCS is functioning properly or direct technician to various diagnostic procedures such as diagnostic charts, symptom diagnosis or BRAKE warning light diagnosis.CHART D - TRACTION OFF WARNING LIGHT ON CONTINUOUSLY & NO DTC SET (BUICK WITH UH8 OR U2A INSTRUMENT CLUSTER)Circuit DescriptionWhen ignition switch is first turned to RUN position, EBTCM goes through a self-test, which lasts 2-4 seconds. During self-test, EBTCM commands TRACTION OFF indicator warning light on. Powertrain Control Module (PCM) can also command EBTCM to set a Code 75 which will illuminate TRACTION OFF indicator.Traction control switch is located either on instrument panel center trim plate or driver's front door trim panel. Switch allows driver to select traction control mode (on/off). When traction control system is turned off, TRACTION OFF warning light comes on.EBTCM monitors transaxle temperature through

Firast you need to have the ABS control module scanned for the fault code that is set when the light is on, then work from that fault code.

Hello
Whenever the ABS warning light comes on in the instrument cluster and it stays on it means the systems electronic control module (computer) has detected a problem in one or more of the inputs to the module; an ABS fault code is present as long as the ABS light is on. So what must be done to correct this? You must have the ABS electronic control module scanned with a special tool to read the fault code, and then a trained technician will diagnose and repair the defective part or wiring. Most times this is a wheel speed sensor (one for each wheel) that gives an erratic signal. While the light is on all you have is regular non-ABS brakes.

Hello
Whenever the ABS warning light comes on in the instrument cluster and it stays on it means the systems electronic control module (computer) has detected a problem in one or more of the inputs to the module, an ABS fault code is present as long as the ABS light is on. So what must be done to correct this? You must have the ABS electronic control module scanned with a special tool to read the fault code, then a trained technicain will diagnose and repair the defective part or wiring. Most times this is a wheel speed sensor (one for each wheel) that gives an erratic signal. While the light is on all you have is regular non-ABS brakes. I assume here the light is on all the time? Until the problem(s) are fixed that are keeping the light on are repaired it will no go off, it can't be reset manually.

Hello
Whenever the ABS warning light comes on in the instrument cluster and it stays on it means the systems electronic control module (computer) has detected a problem in one or more of the inputs to the module, an ABS fault code is present as long as the ABS light is on. So what must be done to correct this? You must have the ABS electronic control module scanned with a special tool to read the fault code, then a trained technicain will diagnose and repair the defective part or wiring. Most times this is a wheel speed sensor (one for each wheel) that gives an erratic signal. While the light is on all you have is regular non-ABS brakes.

this vehicle uses a steering control module and the antilock control module. Both modules get a signal from the steering angle sensor. We found that the steering module didnot show a steering sensor code but the ABS module did show the code.
after checking that the wiring was intact and with good continuity, it was determined that the fault lies in the ABS module.
A new ABS module and configuration confirmed the diagnosis. It's fixed!