After a few days in a garage and starting just fine the previous day, the car does not crank. I checked the battery and tried a different one with no change. I also cleaned the battery terminals and ground connection to the body. I tried "disconnect battery terminals and touch them together over night" with no change. It's been draining the battery pretty badly while sitting so I took the battery leads off while sitting. Not sure if that's contributed to the problem somehow. It started fine couple times with battery terminals reconnected until now. So everything works, instrument lights cone on, just nothing on start. I can hear the fuel pump starting with key on. Car came with only one key, and no remote. I did not find a definitive answer on this board, but perhaps someone figured out a reason for this rather common problem. Thank you for any info.

 

Hi Mad_Russian,

Try starting with the transmission gear selector in Neutral. If the car cranks, you either have an issue with the Park-Neutral switch, or the gear shift lever was not fully seated in Park. That is probably the most common cause of a sudden no-crank.

The second most common cause of a no-crank is probably low battery voltage. Jags need very healthy batteries to function properly. Are you sure the other battery you tried was fully charged and in good health? Did you try jump starting with another vehicle while the other battery was installed? The original battery may have developed an internal fault due to being discharged so often.

The ignition switches can develop intermittent problems - try wiggling the key and pressing it into the lock barrel as far as you can. At least one owner discovered that lubricating the ignition lock solved a no-crank issue.

There are some relays in the starter circuit. Check the Electrical Guide I linked to in your other thread. There are some common problems with relays in these cars. One is corrosion on the terminals of the relay base. Another is failure of the unsealed relays (such as the Light Blue ones) due to water ingress. For the relays that are inside mult-relay modules, such as those behind the passenger-side knee bolster, a common problem is cold or starved solder joints that crack over time and need to be resoldered.

The starters are very difficult to access on these cars, so standard tests to jump the starter terminals or even testing for a voltage drop to the starter is difficult. It is also possible for the starter pinion gear to jam against the flywheel when the battery voltage is low. You can test this by trying to rotate the crankshaft with a socket on the harmonic balancer/crank pulley bolt.

I'm sure others will offer more ideas, and there are LOTS of threads in the forum on no-crank issues.

Regarding the problem with the battery discharging quickly, there are instructions in the forum for diagnosing parasitic current drains. I just tracked one down on a friend's Lincoln that was due to failed diodes in both the alternator rectifier and voltage regulator.

Cheers,

Don

 

Don, I was able to get it started by pushing the key in. Drove it to repair shop where the problem re-appeared again and the car wouldn't start even with key press. They were able to start it by hooking up the starter to the battery directly. At this point, I am very tempted to make a push button start and hide it in the ash tray. (Intead of trying to figure out what is wrong with the ignition switch).

 

Hi Mad_Russian,

There are two possible causes based on your description. One is a worn key or worn tumbler discs in the lock barrel. The other, more common cause, is failure of the electrical ignition switch, which is mounted on the end of the lock barrel. You can test the switch at its electrical connector with an ohmmeter. The Electrical Guide shows which wires should connect at each key position.

Replacing the switch is just a little time consuming but not difficult at all. I did it on both our '88 and '93, and at the link below are photos of the process on our '93:

Welcome to Jag-lovers - Members Photo Viewing Page

Jaguar Merriam shows the ignition switch as still available (part number DBC5675):
Jaguar Parts Center - Call (800) 510-1401 for Genuine Jaguar Parts and Accessories

Rock Auto shows a switch available but they don't show a photo to confirm that it appears to be of the correct design with the correct electrical connector.

David at everydayxj.com has a NOS lock barrel and key:

Jaguar XJ6 XJS XJ8 XK8 Ignition Lock Cylinder - BCC7849


Cheers,

Don

 

Don, thank you for the information. I will definitely check it out.

 

No crank issue solved by bypassing the entire ignition lock and making a button with direct connection to the starter. Works like a charm. I will be integrating it into a ash tray. Doubles as an excellent anti theft feature.

 

UPDATE: Received 2 new keys from Jaguar dealership in Cincinnati. Both keys not only fit nice and tight, but they cured the starting issue, which was probably the result of a badly worn out original key. So something to add to the "no start" bag of tricks for people who are restoring old Jags. Also, keys were 25 a piece, with me providing the blanks. Thanks for everyone's help.