my check engine light on my 94 xjs 4.0 lamps at start up but not every time when you turn the ignition key. failed California smog test as it has to lamp every time ignition is turned before start. I was told I could clean contacts. where is the electrical dash warning light module in the 94 xjs hardtop?

 

My 94 failed CA SMOG for no check engine light.
It needed a replacement lamp that was really difficult to find.
They are a Bayonet Type (I think I may have a few).
Does only the CE light fail to light?
Might be a faulty ground if more than one fails.

 

thank you, the bulb is working but intermittently. When I wait five minutes it does appear at turning the key to position before start. just not every time. So, it fails the test sequence at smog center. pretty stupid as it has new cats and passes emissions test.

 

Tell em the car has two CELs. The dash light and the notification that pops up on trip computer. I managed to circumvent that by simply guiding the tech to look at the screen vs the dash. Hope it works for ya.

 

I have seen other vehicles that would not light the check engine light until the ECU had time to shut down. It may be normal for the light to be off if the key is switched off then switched right back on. However, 5 minutes seems to be excessively long. Is there any aftermarket electrical equipment on the car that may contain capacitors that could be keeping the ECU awake longer than normal?

 

Hey, you are correct sir. I took my xjs to a great jag mechanic in Marin County calif. he backs up what you suggest. after timing it its not five minutes but much shorter. I have no after market add ons that would bring capacitors into the mix. he sent me to a smog shop more familiar with jags and system passed, thanks for your help!