While trying g to diagnose my current non-start issue I attempted to access my fault codes but when I turned the key on and pushed the VCM button nothing appeared on the deeply screen.
TOTALLY BLACK SCREEN! Any thoughts about this, and can that be related to my current no start problem. Faulty ECM for instance. Any thoughts on this will be greatly appreciated.
Gary ,
What year is your car? That can be a big help.
No VCM display almost always means one or more of the solder joints in the display circuity has cracked. Super common problem with TONS of information available if you search the archives.
Try pushing the VCM button and then slapping the top of the dashboard, if the display comes on momentarily and then goes out that’s your problem.
There is absolutely no connection between the blank VCM display and your no start issue.
Hey Groove, in Gary’s first post here:
Engine cranks good but makes no attempt to start. I welcome all suggestions?
he states he has a '94. IIRC my '94 will display nothing but a blank.screen if there is no code or codes to display. It is worth confirming the proper procedure for using the VCM system. Turn the key from off to position II (do NOT turn further to the start [III] position). I wait until the self-test has completed (during which time all caution and warning lights illuminate) to press the VCM button. I do not believe the later cars were plagued with the same solder joint faults as the early ('88 & '89) models that had the digital displays, so while slapping the top of the dash may be therapeutic I don’t believe it is generally helpful from.a diagnostic standpoint!
Mike …
I guess I’m just lazy but I normally don’t memorize the year of everyone’s car from their previous posts.
Could be a bit helpful if it’s always included in a new post or added to the poster’s profile.
I agree, Grooveman. It is helpful.
Thanks Groveland, my XJ40 is a 1994 vin 6988**. Sorry for the oversight. Any idea why my vcm display appears to be dead. It has always had some message on. Could the ecm have anything to do desplay and/or no start.
If it shows the mileage when you turn on the ignition, there’s nothing wrong with the display. Its normal for a blank VCM if there’s nothing wrong that affects the fuel metering.
For instance, if you pulled the coil wire off and pressed the VCM button it wouldn’t show a fault.
Thanks for your reply. The green LCD digital mileage desplay is visible with key on or off but the back light has never worked. The mileage does increase as you drive but outside lighting is required to see them clearly. The error codes have always displayed the yellow LCD message with aid of additional light. I find it hard to believe that error codes would always display when the VCM button was pressed and now since my car refuses to fire there are no errors to display. I just think that is too coincidental.
Did you try changing the cap and rotor like Dennis suggested? If those fail or if the crank position sensor doesn’t work/has a compromised connection, no codes appear. All very normal. The fact that the display backlight is iffy means nothing and is pretty common. These XJ40 idiosyncrasies we all live with can be fixed of course if you have the time and inclination - just like everything else on these old girls.
Just this morning I was looking at a 2005 Lexus for a mate because his car wouldn’t start either. Turned out it was an oxidized terminal at the battery and of course even with the advanced diagnostics available in an upmarket Toyota, the car produced no codes for that situation. Also, if the starter motor was broken he wouldn’t get codes for that either.
Not every issue produces an error code.