XYZ switch or Crank Position Sensor?

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Dangeruss

Well-known member
Mar 28, 2007
104
1
Ontario, Canada
Symptoms;
I replaced all plugs last fall when I did head gaskets but reused the Magnecor wires that had been on for several years as I hadn't had any problems. A couple of days ago I stopped on the way home and after only about a minute it wouldn't restart. After a couple of tries it caught and ran fine the rest of the way home. Since then I have seen the MIL blink a few times indicating a misfire and then go away. I checked the codes and it was Cylinders 1, 4, 5, 7 & 8. I cleared the codes and the next time it happened it was only #4 misfiring. The engine was running fine every time this happened. While investigating possible causes the XYZ switch came up. Today while driving home I had the D, M and S lights blinking and it went into limp home mode with only the upper gears. After a brief stop it restarted and drove home normally, so now I'm thinking XYZ switch, but it also had a new pending crank position sensor fault, which might explain the intermittent misfires.
Questions;
Can the XYZ switch cause a crank sensor code or is that the likely cause?
Can the crank sensor put it into limp home mode?
Any other suggestions?

I have another complete(ish) '04 to pull parts from, just wondering best place to start.
Also, does the search function on here work for anyone else, I keep getting 'server error, try back later'.

Thanks for any help.

EDIT; Battery and charging voltage are normal and all grounds are good.
 
Last edited:
robertofollia

robertofollia

Well-known member
Aug 3, 2005
555
2
My home is where my Disco is
Hi, I am not sure.
The CKP sensor (Crank position) has one specific error code but have never seen throw any of them.
The typical CKP failure is a no-start or a cutting-off in the middle of nowhere and no start but, some 30-0dd minutes later, when the tow truck arrives, it starts 1st time, only to cut off again later (be some 5. 15. or 30 minutes later).
But intermittent misfiring can be caused by arcing of the cables or by a crack in the coils.
The blinking M+S symbols is very likely the XYZ sensor.
But a code reader should give the definitive answer.
Anyway, I have never seen any CKP sensor error code even though there is a code for it.
Hope that helps
Best regards
 
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discostew

Well-known member
Sep 14, 2010
7,724
1,021
Northern Illinois
It kind of sounds like it's a crank sensor. The xyz switch would throw a trans fault and maybe no crank condition. The crank sensor would cause a crank no start condition usually when you park it hot and try to restart it when it's still hot. Technical term I guess would be a hot soak.
Check for spark next time it cranks but won't start. The fuel pump won't run if it doesn't see a crank signal. So don't go down the fuel pump rabbit hole.
 
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Dangeruss

Well-known member
Mar 28, 2007
104
1
Ontario, Canada
Thanks for the tips, I ordered a crank sensor but won't have it until Tuesday and started on the XYZ switch but had to back out because the front bolt was going to break if I tried any harder. I'll let the penetrating oil soak in and have another go on Tuesday when I do the CKP. It took forever to get the link arm nut off without snapping the end off the shaft, working it back and forth 1 degree at a time. They are both original parts with 14 years on them.
 
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Dangeruss

Well-known member
Mar 28, 2007
104
1
Ontario, Canada
Started the crank sensor, got it in relatively easy after dropping the exhaust which was made easy by a recent head gasket job. I think 80% or more of the job is the god damn connector. This should be considered a mandatory job while heads are off, it would have been a piece of cake then. Getting the thing reconnected was easy but getting it back in the clip was brutal, there just isn't enough room or harness slack to get it to line up. Luckily it started raining hard and forced me to take a break and calm down. I unhooked the harness from the cowl, not sure if that actually gave me more slack, but I got the bracket on the connector and then bolted it to the head. It started right up, I'll see how it goes driving it to work the next few days.
 
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ezzzzzzz

Well-known member
Apr 22, 2010
604
7
SE Va
a bad battery can cause these issues. Start with the simple. Check charging system and battery before chasing other potential problems.
 
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Dangeruss

Well-known member
Mar 28, 2007
104
1
Ontario, Canada
Although the battery was fairly new, that and charging were the first thing I checked, along with grounds. I still need to look at roverovers suggestion of the fusebox but the kid has it to go to work tonight. The only twist I don't get is the limp home mode I got with all the transmission lights blinking. Parked and a restart and it went away, only happened once and probably a dozen or more trouble free trips since then.
 
D

Dangeruss

Well-known member
Mar 28, 2007
104
1
Ontario, Canada
A week of driving and no misfire codes, momentary hesitation or other wierdness. Thanks to all who responded and thanks to discostew for talking me away from the XYZ switch.
 
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