code u1900 help

[tenstickyfingers]

hi all just got a Volvo s40 1.8 petrol and a newbie to the forum.I've had the car about three weeks now and the engine light came on after getting it the code is u1900,reset the system all is fine for a week then it comes on again reset then a week later on on it come again,same code u1900. any help and information would be most welcome so I can take it back under warrenty.Many thanks.

[Rudeyboy18]

The most common cause of the trouble code U1900 is a possible defective instrument cluster or an issue with the trailer brake controller, the other possibilties are below, if you need I can send test procedures in order to determine the cause.







Normal Operation

The high speed CAN (Controller Area Network) has an unshielded twisted pair cable, circuits 1908 (WH) and 1909 (BK). The anti-lock brake system (ABS) module, the instrument cluster, the powertrain control module (PCM) and the trailer brake controller are all on the CAN. The total resistance values from the module to the data link connector (DLC) must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in one of the CAN circuits, damage to the DLC C251, damage to one of the communications network module connectors, or damage to an in-line connector.
Possible Causes CAN circuit 1908 (WH) open, short to ground, or short to voltage.
CAN circuit 1909 (BK) open, short to ground, or short to voltage.
DLC C251
ABS module
ABS module C135
instrument cluster
instrument cluster C220b
PCM
PCM C175b or C1381b
trailer brake controller
trailer brake controller C2142b


This was online. Seems consistent with most of the search results.

[Rudeyboy18]

Oh and welcome to the forum. Maybe you should post a thread on "introduce yourself" and post some details and pics of your car. You will get some exposure to the forum then. This forum is probably the friendliest forum ive been on

[tenstickyfingers]

thank you very much,i can now go back to the dealer tooled up so to speak,and thanks for the welcome.

[tenstickyfingers]

this is great thanks if you can send the procedures that would be great. thanks

[tenstickyfingers]

this is great thanks,if you could send some procedures that much appreciated.

[jeffmasson]

this is great thanks,if you could send some procedures that much appreciated.

Did you have any luck fixing this? My car has the same fault clears for about a week the returns then last week would no longer clear. But yesterday cleared on its own then came back later today.

[jeffmasson]

Did you have any luck fixing this? My car has the same fault clears for about a week the returns then last week would no longer clear. But yesterday cleared on its own then came back later today.

I was checking some of my old posts and noticed I never updated this one as the op did not.

It turned out to be my ecm contacts were dirty and just needed a quick spray with contact cleaner.