I have an '89 XJ6/40 base model. It has been running pretty well with issues that do not have to do with the no start problem. I got in, it started right up although the idle was running high/fast, about 2000 rpm. Having grown up with carburetors, I tried to "kick down" the idle with the gas pedal. I thought it might change when the car warmed up and backed the car up, went to put it in D and it just stopped, like someone had turned off the ignition. Now it will not start at all, but cranks just fine. I know the car has OBDI, but the electronic dash info center on the right has been blank/stopped working, and I am not sure if that is where the OBDI codes would be read. I watched a video where you use a wire in the OBDI receptacle to get the code to blink out, but do not know if it will work on my car since the info center is dead. My guess is some ignition problem, crankshaft position sensor, MAF, or ?? I would check the spark plugs, but my spark plug socket will not fit down in the top to take them out. It is too narrow. I checked the rotor/cap and wires; visually all good as far as I can tell anyway. Any suggestions? Thanks.

 

Turn on the ignition. Smack the speedo binnacle with the flat of your hand.
Sometimes the lights will appear and you'll be able to read any codes.

best I can do, sorry

Larry

 

Hi dskul1,

Sorry to hear your Jag is misbehaving. Here are a few random thoughts:

1. If the tachometer shows around 200 rpm while cranking, the CPS is probably working.

2. The diagnostic fault codes are displayed in the small window below the speedometer. To see if your Vehicle Condition Monitor is working, turn the key to Position II (ON) without cranking the starter; press and release the VCM button on the trip computer to the right of the steering wheel and watch for any messages to appear in that small display below the speedometer. DTCs will be in the form of a single digit number, possibly prefixed by the words Fuel Fault or the letters FF, as in FF8. The definitions for each DTC are given in the Haynes manual, which you can download at the link below. It's missing a couple of chapters, but I think the code definitions are there in the Emissions section:

https://www.mediafire.com/?hx8bttsy4kxxr

3. The inoperative sections of your Instrument Cluster may be due to cold or cracked solder joints on the circuit board(s) inside the IC. Search this forum and the Jag-Lovers forum archives for posts on this issue, which is well-known.

Another possibility is loose or corroded IC electrical connectors. There are four connectors, one on each end of the rear surface of the IC, and one on each of two short pigtail wiring harnesses. You can access the latter two connectors from underneath the IC after removing the knee bolster. To access the connectors on the back of the IC it is easiest to remove the four hex head screws that secure the IC to the dash - two screws at each end. See my photo album on removing the IC at the link in my signature. Depending on how large your hands are, you may be able to reach up behind the IC and check the integrity of the connectors, but to check them for corrosion you'll need to disconnect the IC.

Larry's suggestion to smack the binnacle/IC may help reveal a problem with either bad solder joints or loose connectors.

4. The sudden no-start is unusual and makes me wonder if something was jolted loose when you shifted into gear at high engine rpm. The first thing that comes to mind is the inertia switch, which shuts off the fuel pump and other circuits in the event of a collision. If the car moved suddenly when you shifted into gear perhaps the inertia switch was triggered. On our '93, it's a black plastic box in the outer left corner of the driver's footwell partially hidden by carpet. There's a small plunger type button that pops up when the switch is tripped. Press it back down to reset the switch.

5. A known issue on early XJ40s was a damaged electrical connector somewhere between the fuel pump relay and the fuel pump. Search this forum and the Jag Lovers forum archives for details.

6. Another possibility is that a fuse might have been blown when you shifted into gear at high rpm, or an electrical connection might have been jolted loose. It might be worth checking all the fuses in the three fuseboxes, and all the electrical connectors and wiring in the engine bay, including the engine ground strap, the two grounds on the intake manifold, and the ground on the firewall/bulkhead behind the cylinder head.

7. You mentioned that you checked the distributor cap and rotor - what about the king lead from the distributor cap to the coil? Could that have been pulled loose from the coil? Also check the integrity of the electrical terminals on the coil. If it's the original coil the plastic may be cracked or crumbling, as happened to ours.

8. A very common cause of no-start on Jags is low battery voltage. If the battery voltage falls much below 11V while cranking, the Engine Control Module (ECM) will not trigger the ignition to fire. I don't know why the sequence of events you describe would indicate low battery voltage but it might be worth checking the voltage sag while cranking just in case. Often a no-start condition is the result of more than one component malfunctioning.

Please keep us informed.

Cheers,

Don

 

I have looked at the tach, and there is no rpm,s indicated. Needle does not move. So if I understand correctly, that would be the crankshaft position sensor, correct? I will, when the sun comes up, try some of the other diagnostics.

 

Assuming your tachometer is operative, it should show about 200 rpm while cranking the engine to start. 0 rpm is an indication that the CPS has failed or there is a problem with its electrical connection. It is worth checking its electrical connector for oil contamination and to ensure that all of its pins are secure. I once had a problem with a new CPS because one pin was pushed out of the back of the connector when I pressed the two halves of the connector together.

Cheers,

Don

 

Well, I finally had a chance to look at the car and try some of the things you have all suggested. I am a little bit embarrassed to say it was just a loose wire; the wire from the coil to the distributor had somehow come adrift. I had not worked on or done anything near that wire for weeks, but when I checked it, it looked like it was secure, but it was not. I am happy to say that that was the only problem in getting it started. Now I can start to get to work on the other things that need attention. Hope I didn't waste too much of people's time. Thank you!