Flickering lights
#1
Flickering lights
Hi All,
1998 3.2 sport, low mileage and used as a ' weekend ' car. I started it a couple of dags ago and noticdd the light and dashboard lights flickering. After a couple of minutes the dash display reported gearbox and stability faults. The gearbox gave a very hard thump when I put it into reverse. I switched off and today fully charged the newish quality battery. This time the lights would not come on. I had originally thought it may be alternator but now think it is an ecu issue?
1998 3.2 sport, low mileage and used as a ' weekend ' car. I started it a couple of dags ago and noticdd the light and dashboard lights flickering. After a couple of minutes the dash display reported gearbox and stability faults. The gearbox gave a very hard thump when I put it into reverse. I switched off and today fully charged the newish quality battery. This time the lights would not come on. I had originally thought it may be alternator but now think it is an ecu issue?
#2
It may be a weak battery or perhaps the instrument cluster is failing? The cluster is part of the CAN communication buss and if the buss is not communicating correctly, you'll get a number of reported failures. These cars are very sensitive to battery voltage so I'd start with that check...
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Al 4693 (01-09-2024)
#3
Flickering lights
Dear David,
thanks for your reply. I too suspected battery, athough it's about 12 months old and regularly charged with my c-tek charger. I charged it fully before starting today on the indacted fully charged battery when I got all of the faults, so as you suggest it may be instrument cluster related. The very hard lurch going into reverse and the gearbox fault warning is odd however.
thanks for your reply. I too suspected battery, athough it's about 12 months old and regularly charged with my c-tek charger. I charged it fully before starting today on the indacted fully charged battery when I got all of the faults, so as you suggest it may be instrument cluster related. The very hard lurch going into reverse and the gearbox fault warning is odd however.
#4
Otherwise, low alternator (and battery) voltage often causes false gearbox faults to be desplayed, hard shifts and restricted performance.
#5
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#9
#10
Flickering lights.
Hi Randy S.
Thanks for that advice, I checked the earth strap and it does appear to be secure. Further to the advice to measure the voltage to the battery with a multimeter, static it measured 12.1v and running 13.4v but surging to 15.3v momentarily with a drop in engine revs, which to my mind suggests a failing alternator?
Thanks for that advice, I checked the earth strap and it does appear to be secure. Further to the advice to measure the voltage to the battery with a multimeter, static it measured 12.1v and running 13.4v but surging to 15.3v momentarily with a drop in engine revs, which to my mind suggests a failing alternator?
#11
12.1 static voltage means that the battery is at about 50% charge. You should immediately fully charge it to prevent its sulfation (loss of capacity).
The fluctuation of the alternator voltage may not mean there is something wrong with it. I had similar fluctuation on my car once and found that it was caused by deteriorated crimp of the battery positive terminal to the cable (the one that runs from the battery to the "megafuses" in front of the spare tyre). The crimp looked fine on the outside but it was not good inside. I diagnosed this when I found out that the section of the positive cable near the battery terminal was rather hot after just a few minutes of car idling.
It appears that a poor contact in the crimp (causing some sparking inside) causes the current flow into the battery to rapidly fluctuate which confuses the alternator and causes it to excessively fluctuate its output. I suggest you first check whether any of your battery cables (positive or ground) is getting warm/hot near connections to its terminals. If yes, you will need to replace that cable. Battery cable crimps looking good on the outside but bad inside seems to be a fairly common problem on our cars. I made new positive and negative cables myself - I bought a length of heavy gauge cable (100% copper), suitable cable terminals and a hydraulic crimping tool (you need hydraulic because of the size of the terminals). Never had flickering again. Perhaps you can find a shop which can make these cables (they are not cheep as Jaguar parts).
In addition to checkig the temperature of the cables, you should also open the"megafuse" box, undo the nuts, clean well all connecting surfaces (cable terminals to the fuses) and reinstall. Be careful not to overtighten the nuts. Also check the engine ground strap connections. Only if the cleaning of connections and replacing the battery cables (if found to have poor crimps) does not solve the problem, then you can suspect the alternator. If you determine it is the alternator, you may need to only replace its Voltage Regulator which is not too expensive and is very esy to do.
The fluctuation of the alternator voltage may not mean there is something wrong with it. I had similar fluctuation on my car once and found that it was caused by deteriorated crimp of the battery positive terminal to the cable (the one that runs from the battery to the "megafuses" in front of the spare tyre). The crimp looked fine on the outside but it was not good inside. I diagnosed this when I found out that the section of the positive cable near the battery terminal was rather hot after just a few minutes of car idling.
It appears that a poor contact in the crimp (causing some sparking inside) causes the current flow into the battery to rapidly fluctuate which confuses the alternator and causes it to excessively fluctuate its output. I suggest you first check whether any of your battery cables (positive or ground) is getting warm/hot near connections to its terminals. If yes, you will need to replace that cable. Battery cable crimps looking good on the outside but bad inside seems to be a fairly common problem on our cars. I made new positive and negative cables myself - I bought a length of heavy gauge cable (100% copper), suitable cable terminals and a hydraulic crimping tool (you need hydraulic because of the size of the terminals). Never had flickering again. Perhaps you can find a shop which can make these cables (they are not cheep as Jaguar parts).
In addition to checkig the temperature of the cables, you should also open the"megafuse" box, undo the nuts, clean well all connecting surfaces (cable terminals to the fuses) and reinstall. Be careful not to overtighten the nuts. Also check the engine ground strap connections. Only if the cleaning of connections and replacing the battery cables (if found to have poor crimps) does not solve the problem, then you can suspect the alternator. If you determine it is the alternator, you may need to only replace its Voltage Regulator which is not too expensive and is very esy to do.
Last edited by M. Stojanovic; 01-11-2024 at 06:09 AM.
#13
The first step when you run into any electrical glitch in these cars is to do a hard reset. Remove the negative cable from the battery, touch it against the positive terminal for 10 seconds, then reconnect it to the battery. Sometimes it's just that simple. Many times, actually. Try that first before moving on to the other suggestions.
#14
Flickering lights
Thanks for that tip re the hard reset. Have charged battery and tested again with multimeter. Shows 12.6v at battery but ranging voltage when running from 13.1v to 15.7v with intermittent drops in tickover engine speed as if alternator is tripping on and off with accompanying strange noises. Local garage booked up at present, they suspect alternator problem. Will update when problem identified and rectified.
#16
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