Hi Mark,

I normally use LEDs, and label them with paper tape, but in this case I expect it to fail long enough for testing, going on what the customer has told me.

A google search has thrown up the below info on the code.

Fault Code Title
1310 Control of the Injectors
Type of fault
Short-circuit to earth Short Circuit -
Short-circuit to +Vbat Short Circuit +
Detection
Detected if voltage across terminals of the HSD is less than 0.5 V,
Detected if voltage across terminals of the HSD is more than 4.8 V.

Symptoms
Engine starting impossible.
Running engine stalls.

Fault light
On

Recovery method

Inhibition of the injections and of discharge by the injectors.
Engine speed limited to 2000 rpm.
If the fault appears while the engine is running and then persists, the inhibition of the injections results in an engine shut-down.
However, if the fault disappears, the injections are given the chance to resume, and for this reason there is no engine shutdown
requested.

Electric fault
Short Circuit - on terminal 80
Short Circuit - on terminal 72
Short Circuit - on terminal 64
Short Circuit - on terminal 56
Short Circuit - on terminal 76
Short Circuit - on terminal 68
Short Circuit - on terminal 60
Short Circuit - on terminal 52
Short Circuit + on terminal 80
Short Circuit + on terminal 72
Short Circuit + on terminal 64
Short Circuit + on terminal 56
Short Circuit + on terminal 76
Short Circuit + on terminal 68
Short Circuit + on terminal 60
Short Circuit + on terminal 52
Type of fault
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit -
Short-circuit to earth Short Circuit +
Short-circuit to earth Short Circuit +
Short-circuit to earth Short Circuit +
Short-circuit to earth Short Circuit +
Short-circuit to earth Short Circuit +
Short-circuit to earth Short Circuit +
Short-circuit to earth Short Circuit +
Short-circuit to earth Short Circuit +
* HSD: High Side Drive
LSD: Low Side Drive

If the above info is correct, one or more of the four inj positives is going either high or low. It will probably be an injector but at least it gives me somewhere to start.