Hi everyone ,
I had to drop working on my project car a few months back and allowed the battery to go dead .
Now she won't fire , cranks with ease.
1996 XJR
It had a discharge issue I'd repaired with a used body module. It there something I need to reset ?
Always started on the first crank before the layoff.
thanks again
Regards
Fmfz12007

 

In the heat of battle when the voltage drops below 11.4 volts there is not enough to run the engine ECU but the starter will rotate just fine . A full battery charge is 12.75 volts . The starter rotation enable comes through the BCM .

 

 

I think the battery is doing its job , but I will check the voltage later today . Seems I've read there is a fuel pump reset . Could it have cut off fuel ?
I'll play with it some this evening, having it re painted , I thought I had all the mechanical issues solved

 

There is not a fuel pimp reset per say but a fuel pump running verification and then you can work the issue from there .

With the key in the on position before start position you should have the # 1 fuel pump turn on for 4 seconds only . You have a # 2 fuel pump on the SC engine that can be used as a troubleshooting tool but will leave alone for simplicity . Without the engine turning over you can hear the pump running from the cabin . You can also put your finger on the relay to feel for the 2 clicks on - off .

The fuel pump comes back on with a 3rd click of relay from the CKPS seeing engine rotation for the duration of the drive .

On a personal experience after my car was down for some exhaust repairs it would not start . Turned out the voltage available to the ECU was 9.6 volts from a fully charged battery but the starter would rotate the engine fine . The starter solenoid was shorting out to case / frame ground with the motor brushes pigtail removed .

Editing

 

Are you thinking of the Inertia Switch?




Very unlikely it's tripped.

Graham

 

I was wrong on the reset term .

The inertia / crash switch can be overridden by a paperclip jumpering the 2 white wires . It's on the RH side for both LHD and RHD just fwd of the ECU .They can be intermittent on pressing the button down to reset or tripping in the first place from what I understand .

 

Hi , thanks for the help. I did a reset on the inertia switch , didn't seem to change anything. I then did a hard reset, battery disconnect , started right up.
RPMs were high and I guess I have an oil leak on the right side , valve cover that needs attention now I'm thinking about putting the old BCM back on to see if this is my issue . It was taken from a parts car I keep around. I'm pretty sure the fuel pump was silent , construction near me made it hard to hear if it was functioning. I have hearing problems, but not that bad lol.
I'll try it again tomorrow, same results I may be back for help .
Regards
Fmfz12007