2005cmax 1.8 petrol messsage comes up (speed limited mode ) gote code u1900 of greenflag guy dtc says code d900 & e510

Switching on the aircon will rob the engine of a handful of horses but most people most of the time won't notice. Could be the problem goes deep.

By 2007 most vehicles were digital computer controlled so it isn't easy to guess what is going on. I think you need a guy with a good scanner who knows how to use it who can gather and interpret live data.

Take it to a qualified repair shop, unless you know about C.A.N - controller area network - serial data communication network between modules . U1900 -20 - ic states that one of the 8 or 10 or more modules on your vehicle has stopped talking .
U1900 CAN Communication Bus Fault-Receive Error RCM REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error Occupant Classification Sensor REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error SJB REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error DVD Player REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error Audio Control Module (with Navigation) REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error Audio Control Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error SDARS REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error Retractable Running Board Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Recieve Error ABS Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Recieve Error Parking Aid Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error 4WD Control Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Receive Error Instrument Cluster REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication BUS Fault - Receiver Error DSM REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 .

P1270 - Engine RPM/Vehicle Speed Limiter Indicates the vehicle has been operated in a manner which caused the engine or vehicle to exceed a calibration limit. The engine rpm and vehicle speed are continuously monitored by the PCM. The DTC is set when the rpm or speed fall out of calibrated range. For additional information on the engine rpm/vehicle speed limiter, refer to Section 1, Electronic Engine Control (EC) System , Powertrain Control Software.

• Wheel slippage (water, ice, mud and snow)
• Excessive engine rpm in Neutral
• Vehicle drive at a high rate of speed

The DTC indicates the vehicle has been operated in a manner which caused the engine or vehicle speed to exceed a calibrated limit.

If you would like help we would need the DTC - diagnostic trouble code .Is their a Reduced Engine Power Mode message showing on the instrument cluster ?
Reduced Engine Power Mode
When the PCM detects a problem with the throttle actuator control (TAC) system the PCM enters one of the following Reduced Engine Power Modes:
• Acceleration Limiting--The control module will continue to use the accelerator pedal for throttle control, however the vehicle acceleration is limited.
• Limited Throttle Mode--The control module will continue to use the accelerator pedal for throttle control, however the maximum throttle opening is limited.
• Throttle Default Mode--The control module will turn off the throttle actuator.
• Forced Idle Mode--The control module will perform the following actions:
- Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned off.
- Ignore accelerator pedal input.
• Engine Shutdown Mode--The control module will disable fuel and de-energize the throttle actuator.
IF you do not know this your best bet would be to take to a qualified repair shop .
DTC P0506
DTC P0507
The throttle actuator control (TAC) motor is controlled by the powertrain control module (PCM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the PCM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the PCM commands the throttle plate open allowing more air to pass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.

Do you know what a serial data network is ? With all the computers car makers put on thier cars these day's they need a communication network for them to talk ,share info. on etc. U codes are codes for the network . A module could be down ,could be a wiring problem . A shorted module or bus wire can bring down the whole vehicle. Could cause the vehicle not to start ,systems not to function . How did you pull this code ,with what scan tool or code reader ? Did it come from the PCM - engine computer ? Need a up scale professional scan tool to check all module's on the vehicle , need to pin point the module that is causing the problem .
U1900 CAN Communication Bus Fault - Receive Error 4WD Control Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault - Receive Error ABS Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault - Receive Error DSM REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault - Receive Error Instrument Cluster REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault - Receive Error Occupant Classification Sensor Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault - Receive Error Parking Aid Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault - Receive Error RCM REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 . U1900 CAN Communication Bus Fault - Receive Error Retractable Running Board Module REPAIR all other DTCs first. CLEAR the DTCs. CYCLE the key OFF then ON and wait 10 seconds. REPEAT the self-test. If DTC U1900 is still present, REFER to Section 418-00 .
016 CAN Communications

SECTION 418-00: Module Communications Network 2007 Explorer/Mountaineer/Explorer Sport Trac Workshop Manual DESCRIPTION AND OPERATION Procedure revision date: 08/02/2006 Communications Network Vehicle communication utilizes both medium and high speed controller area network (CAN) communications. CAN is used for many modules to communicate with each other on a common network. CAN in-vehicle networking, is a method for transferring data among distributed electronic modules via a serial data bus. Without serial networking, intermodule communication requires dedicated, point to point wiring resulting in bulky, expensive, complex, and difficult to install wiring harnesses. Applying a serial data network reduces the number of wires combining the signals on a single network. Information is sent to the individual control modules that control each function.
The vehicle has 2 module communication networks:

• Medium speed (MS) CAN
• High speed (HS) CAN

Both networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one scan tool to be able to diagnose and control any module on both networks from one connector. The DLC can be found under the instrument panel between the steering column and the audio unit.
Network Topology

Module Name Network Type Termination Module Anti-lock brake system (ABS) module HS-CAN No Audio control module (ACM) MS-CAN No Digital versatile disc (DVD) player (if equipped) MS-CAN No Driver seat module (DSM) (if equipped) MS-CAN No Electronic automatic temperature control (EATC) module (if equipped) MS-CAN No Four wheel drive (4WD) control module (if equipped) HS-CAN No Instrument cluster (IC) (gateway module) HS-CAN
MS-CAN Yes
Yes Occupant classification sensor (OCS) module HS-CAN No Parking aid module (PAM) (if equipped) MS-CAN No Powertrain control module (PCM) HS-CAN Yes Power running board (PRB) module (if equipped) MS-CAN No Restraints control module (RCM) HS-CAN No Satellite digital audio radio system (SDARS) (if equipped) MS-CAN No Smart junction box (SJB) MS-CAN Yes Transmission control module (TCM) (if equipped) HS-CAN No
MS-CAN Network Operation
The MS-CAN network communicates using bussed messages. The MS-CAN has an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. In addition to scan tool communication, this network allows sharing of information between all modules on the network.
The MS-CAN is a medium speed communication network used for the following modules:

• SJB
• Audio unit
• Instrument cluster
• DSM (if equipped)
• DVD player (if equipped)
• EATC module (if equipped)
• Parking aid module (if equipped)
• Satellite audio receiver (if equipped)
• Power running board module (if equipped)

HS-CAN Network Operation
The HS-CAN network communicates using bussed messages. The HS-CAN network uses an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. In addition to scan tool communication, this network allows sharing of information between all modules on the network.
The HS-CAN is a high speed communication network used for the following modules:

• PCM
• TCM (if equipped)
• RCM
• ABS module
• Instrument cluster
• Occupant classification sensor module
• 4WD control module (if equipped)

Network Termination
The CAN network uses a network termination circuit to improve communication reliability. The network termination of the CAN bus takes place inside the termination modules by termination resistors. Termination modules are located at either end of the bus network. As network messages are broadcast in the form of voltage signals, the network voltage signals are stabilized by the termination resistors. Each termination module has a 120 ohm resistor across the positive and negative bus connection in the termination module. With 2 termination modules on each network, and the 120 ohm resistors located in a parallel circuit configuration, the total network impedance, or total resistance is 60 ohms.
Network termination improves bus message reliability by:

• stabilizing bus voltage.
• eliminating electrical interference.

Gateway Module
The instrument cluster is the gateway module, translating HS-CAN to MS-CAN and vice versa. This information allows a message to be distributed throughout both networks. The instrument cluster is the only module on this vehicle that has this ability.

Did you ever get to the bottom of this? I am having exactly the same issue with my 2006 Focus 1.6 tdci

No messaage of reduced engine power ? Your vehicle has electronic throttle control . Has four position sensors , two are located in the gas pedal ,an two in the throttle body . The PCM uses these sensor to know how much to open the throttle plate ,allowing more air into the engine . How did you read this code an where did you read it's definition at ? This is not a code for your vehicle . Some time cheap code readers get them wrong .
DTC P2120: Accelerator Pedal Position (APP) Sensor 1 Circuit
DTC P2122: Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage
DTC P2123: Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage
DTC P2125: Accelerator Pedal Position (APP) Sensor 2 Circuit
DTC P2127: Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage
DTC P2128: Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage
DTC P2138: Accelerator Pedal Position (APP) Sensor 1-2 Correlation

DTC P1516: Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance
DTC P2101: Throttle Actuator Position Performance
DTC P2119: Throttle Closed Position Performance
DTC P2176: Minimum Throttle Position Not Learned

If one of this position sensors is bad it will throw the PCM into a
Reduced Engine Power Mode
When the ECM detects a condition with the TAC system, the ECM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
• Acceleration limiting--The ECM will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
• Limited throttle mode--The ECM will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
• Throttle default mode--The ECM will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The ECM will perform the following actions:
- Limit engine speed to idle by positioning the throttle position, or by controlling the fuel and spark if the throttle is turned off.
- Ignore the accelerator pedal input.
• Engine shutdown mode--The ECM will disable fuel and de-energize the throttle actuator.


017 Accelerator Pedal Position Sensors
Drive by Wire Function and diagnostics by Wells

You will need the help of the Ford dealer on this as special equipment on the handas of a factory trained tech is required to diagnose these codes.

DTC P2104 - Forced Idle Mode

In this mode, the throttle plate is limited to idle speed and limited vehicle speed (about 30mph) only. This can be caused by 2 or more APPS sensor failures or a stuck throttle related DTC.

The above was from the following link:

http://articles.d-tips.com/art8.html

make sure your batt cables are tite--may need new one or cud hav charging problems--for codes you need to go Chiltons online or ask a dealer tech--however dont go replacin parts till you know for sure cause its $$ and discouraging Consult others 1st