sierrafery
Well-Known Member
What i was trying to say was that it might be a fusebox issue(bad contact within it) not a blown fuse cos a blown fuse from one of those you mentioned would have affected other things too
Thanks Sierrefery I agree with you, Now the systemematic task of working through the wiring diagramme with a multi meter and Shims Nanocom. I am sure that this will give me hours of entertainment . The only thing I don't underdstand is why the voltages reported on my scanner at the BCU were lower than what I measured at the cigar lighter?
sierrafery
Well-Known Member
Differencies in voltages between circuits is not unusual, depends on the load
Hi Guys.
I have diagnosed the fault using Shims Nanocom.
Was able to run fuel pump using test function.
The engine warning light is lit on dash ( Should this stay on if engine not started?)and ecu reports.
P1668 anti theft serial link fault signal too low once and too high 3 times.
Disabling imobiliser did not clear this.
I have got the bypass link ARM4956 will now research how to fit this.
Any advice Sierrafery?
I have diagnosed the fault using Shims Nanocom.
Was able to run fuel pump using test function.
The engine warning light is lit on dash ( Should this stay on if engine not started?)and ecu reports.
P1668 anti theft serial link fault signal too low once and too high 3 times.
Disabling imobiliser did not clear this.
I have got the bypass link ARM4956 will now research how to fit this.
Any advice Sierrafery?
sierrafery
Well-Known Member
was the alarm set to "not fitted" too? cos the main immobiliser is part of that, only disabling the passive immobiliser is not enough.... as @discool said that AMR4956 is useless
Thanks for the advice guys. All alarm options had been disabled.
However I have now mhad a breakthrough. I am not certain if it is a permenant fix, but the car is running again!
I used the Nanocom to test everything and the only consistent fault was the serial link.
I restored all security settings to normal and tried to fault find further.
I have just had the windscreen fixed which stopped a water leak that was running down the Lhs A pillar and along a wiring harness through the connector. I dismantled this connector and found corrosion within the connector - see photo. I cleaned up the connector and gently filed the terminals( with the power off). I tested it and still same fault. I decided to start the car using the paper clip and switch on the fuel pump with the Nanocom. It was cold so I also put on the heater whilst I scrolled through the ECU and BCU pages - no faults found. I shut down the car, replace the relays and tried to restarted the car. It worked and ran fine!!
All I can think is that when wet, the corrosion gave a good contact, however as it started to dry out, the resistance went
high on one or more of the terminal.
As far as the fix is concerned, cleaning the terminals will have improved the connection. The higher residual voltage of the battery may have then overcome any remaining poor contact. The proof of the pudding will be in the cold light of day tomorrow morning.
However I have now mhad a breakthrough. I am not certain if it is a permenant fix, but the car is running again!
I used the Nanocom to test everything and the only consistent fault was the serial link.
I restored all security settings to normal and tried to fault find further.
I have just had the windscreen fixed which stopped a water leak that was running down the Lhs A pillar and along a wiring harness through the connector. I dismantled this connector and found corrosion within the connector - see photo. I cleaned up the connector and gently filed the terminals( with the power off). I tested it and still same fault. I decided to start the car using the paper clip and switch on the fuel pump with the Nanocom. It was cold so I also put on the heater whilst I scrolled through the ECU and BCU pages - no faults found. I shut down the car, replace the relays and tried to restarted the car. It worked and ran fine!!
All I can think is that when wet, the corrosion gave a good contact, however as it started to dry out, the resistance went
As far as the fix is concerned, cleaning the terminals will have improved the connection. The higher residual voltage of the battery may have then overcome any remaining poor contact. The proof of the pudding will be in the cold light of day tomorrow morning.
Shimsteriom
Master Procrastinator
So, does it still work? 
Fault reoccurred today. I started the car, drove for 2 mins, parked up for 3o mins without locking the car. Get back in ignition came as normal then would not crank.
Relocked car and retried - still no luck. Popped the starter relay out and started with paperclip. Car ran fine and will now start when ignition used. No faults recorded on ECU or BCU. Voltage at cigar lighter was 12.4V.
I have not given the corroded connector a thorough clean yet. Faulty relay?
Relocked car and retried - still no luck. Popped the starter relay out and started with paperclip. Car ran fine and will now start when ignition used. No faults recorded on ECU or BCU. Voltage at cigar lighter was 12.4V.
I have not given the corroded connector a thorough clean yet. Faulty relay?
sierrafery
Well-Known Member
You can rule out the relay simply by putting R3(headlamp wash) instead of it
sierrafery
Well-Known Member
For the future, in places where water or moister can have bad effect use this http://www.nanoroad.co.uk/auto-coatings/4-nano-protech-electric.html it's the bee's knees in this area, treating both fuseboxes and exposed connectors with it can keep you troublefree, since i've discobered it few years ago i keep using it once a year on everything even in the ECUs and no problems caused by corrosion or bad contacts so far
Fault reoccurred today. I tried Sierrafery's suggestion of replacing starter relay with R3. No improvement. I jumped out the starter relay with my trusty paper clip and the engine ran fine. I pulled the fuel pump relay with the engine running and the engine died in 2 seconds. Stopped the car. Replaced all relays and tried to start it - no luck. Used paper clip ran car for 5 mins, moved it on my drive. Replaced all relays and now it starts fine. Using the diagnostics
Onto ECU P1668 = Anti-thrift alarm serial link fault drive cycle A occurred 2 times, signal too high fault is currently not present. What do you think is faulty?
Onto ECU P1668 = Anti-thrift alarm serial link fault drive cycle A occurred 2 times, signal too high fault is currently not present. What do you think is faulty?
That's the Passive Immob I think ... set by the main dealers ... only the drivers side opens ?...
Dragged this off of the web;
SYMPTOM VERIFICATION OF ACTIVATED PASSIVE IMMOBILIZATION
1. Unlock the vehicle and wait one minute.
2. With the ignition off, verify that the anti-theft alarm LED in the instrument pack blinks slowly.
3. Turn the ignition key to position "II" and verify the alarm LED is on continuously. This indicates an immobilized condition.
4. Check that Passive Immobilization is on by attempting to start the vehicle with the LED on continuously.
5. If the vehicle does not start, confirm that Passive Immobilization is turned on as follows:
^ Turn off ignition and remove the key.
^ Press the unlock button on the plip once.
^ Attempt to restart the vehicle within 30 seconds.
^ If the vehicle starts normally, Passive Immobilization is activated. The BCU must be replaced or reprogrammed by Land Rover after contacting the LRNA HelpLine.
hope this helps ...
Edited to add: http://www.landroversonly.com/forums/f40/fault-code-p1668-28431/
sierrafery
Well-Known Member
very hard to tell, seems like a bad contact somewhere, at the ECU or fusebox
