JK99 wrote:I experienced a similar problem with the immobiliser code early this year. Both the green and the red lights were on. It turned out that fuse F1, under the bonnet, had blown. When a new fuse was inserted, the immobiliser worked.
But when I started the engine, the fuse blew again, and immobiliser stopped working. Both red and green lights showed again.
The problem turned out to be a seized (frozen) EGR solenoid. Once this was removed, cleaned out , unfrozen and refitted, the car worked fine. However, it was not cheap to fix.
There have been a good number of reports of Red+Green on the keypad over recent months - keypad/ECU error. JK's remarks about F1 (engine bay) got me wondering, and his reported link to the EGR circuit, so I pored over a good number of circuit diagrams last night.
Manuals list engine bay F1 (10A) as protecting
- EGR control box (= EGR relay) #830
- Preheater (glowplug) relay (coil, not GP supply)
There is no mention of F1 supplying Immobiliser.
Turning to the circuit diagrams, it seems that
(a) EGR relay #830 was only fitted to
LHD P8B/XUD11ATE engines (source 518-05/10, 10a...10c)
but
(b) fusing for this relay was repeatedly shifted across the XM fuseboards:
RP 6381-6568, fused at engine bay F1 **
RP 6568-6811, fused at engine bay F5
RP 6811-7084, fused at main board F31 and via main board SH (shorting link)
RP 7084-7252, ditto
For all
RHD P8B/XUD11ATE engines (source 518-24/10, 10a...10c)
LHD THY/2.5 engines (source 518-05/20, 20a...20d)
RHD THY/2.5 engines (source 518-25/20, 20a...20c)
(a) No EGR relay was fitted
(b) EGR recycling pump (vacuum pump) #759 had unfused supply, fed straight from IGN switch.
Conclusions
From the circuits, it appears that only some early LHD cars (** above) had fusing of the EGR relay ('control box') at engine bay F1.
I have not been able to identify how this fuse blowing could affect keypad/immobiliser, as they do not share supplies.
It's possible that JK's car wiring had been altered, or that the high current rush (which caused F1 to blow) also put strain on another connection (maybe a contact in the IGN switch), which threw up the Red+Green keypad fault.
Unfortunately, this probably sheds more light on EGR/Relay/Fusing arrangements than it does on keypad/immobiliser.