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isdyl22 Newbie
Age: 53 Zodiac: Joined: 05 Apr 2021 Posts: 7 Location: Woking
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Posted: Wed Apr 07, 2021 8:34 Post subject: Glow plugs stay on |
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Hi - I have a '94 2.8 Shogun which I've had for over 10 years. I've had various issues with glow plugs over the years - usually the solenoid has failed, or the plugs wear out. This week though the problem is that the plugs seem to stay on indefinitely and run the battery flat! When I go to start it however the dash light just flicks on and off in a micro second, but the engine starts fine. (after I charged the battery back up). When I connect a test lamp to the plug bus bar I can see that the plugs just stay on when the engine is running. Could this be a failed glow plug ecu, or glow plug temp sensor maybe? Any ideas would be welcome please. |
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Posted: Wed Apr 07, 2021 8:34 Post subject: Google Ads keep the POCUK free to join! |
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emax LifeTime Member
Age: 67 Zodiac: Joined: 02 Aug 2007 Posts: 2277 Location: Purleigh
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Posted: Wed Apr 07, 2021 14:03 Post subject: |
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As you say the plugs stay on indefinitely, I am not sure it will help, but the plugs should stay on after starting, I think for a few minutes or until the engine is warmed. |
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isdyl22 Newbie
Age: 53 Zodiac: Joined: 05 Apr 2021 Posts: 7 Location: Woking
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Posted: Wed Apr 07, 2021 16:58 Post subject: |
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Hi - thanks for your reply. I tried to post a video which I had followed but I'm not allowed to apparently. It definitely showed the glow plug bus bar receiving voltage for about 2 or 3 seconds before cranking, but zero voltage after that, which is what my Shogun used to do. I tried swapping out the ecu just now but it made no difference. I've just ordered a glow plug temperature sensor so will see if that helps. The one that is installed has a resistance of 1.6 k ohms but I'm struggling to find information as to what it should be. |
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isdyl22 Newbie
Age: 53 Zodiac: Joined: 05 Apr 2021 Posts: 7 Location: Woking
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Posted: Sat Apr 10, 2021 11:47 Post subject: |
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Hi all, so I changed the temperature sensor located next to the forward-most glow plug but still no difference. I have so far changed the control unit/ecu located in the passenger side kick panel, and the temperature sensor. I've read that there is also a timer unit located under the ignition key area? I had a quick look and there is a couple of plugs hanging down loose that look like they should be plugged into something! Does anyone know what the timer looks like please because I can't see anything obvious that is missing its wiring plug!
Thanks |
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Mark3 LifeTime Member
Age: 61 Zodiac: Joined: 13 Feb 2009 Posts: 4016 Location: Rainham Village, Essex.
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Posted: Sun Apr 11, 2021 11:17 Post subject: |
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A correctly working 2.8 heater plug system will function thus;
Ignition only from cold heat plugs for 10 seconds, warning light on dash will illuminate for around 4 seconds
once running the heater plugs will remain powered for around 2 minutes, maybe for as long as 2.5 minutes
warm starting means the heater plugs will heat for less time depending on engine temperature until sufficient engine temp is reached that they dont come on at all. |
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iam_TJ LifeTime Member
Joined: 10 Apr 2013 Posts: 351 Location: Europe
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Posted: Sun Apr 11, 2021 22:06 Post subject: |
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Have you checked the relay? Sounds to me like 'sticky contacts' in a relay has caused them to effectively fuse together. This is a relatively common problem in relays of all types where the arcing between the contacts as they make or break eventually causes one side to form a pit and the other a spike (melts the material) until they stick together. I've fixed such problems with fine emery paper many times as long as the relay case will pop off. |
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isdyl22 Newbie
Age: 53 Zodiac: Joined: 05 Apr 2021 Posts: 7 Location: Woking
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Posted: Sat Apr 17, 2021 8:31 Post subject: |
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Hi - thanks for the suggestion, but no it's not that. The solenoid (next to the battery) is energised as soon as the ignition is on and stays energised keeping the plugs on. It won't go off until I remove the smaller wire, and then it clicks off nicely. I think from what I've read that there is a timer relay somewhere up near the ignition switch behind the drivers side (RHD) speaker, but I haven't located it yet! I've ordered a push button for the dash as a temporary solution as I can drive the car but currently have to open the bonnet and disconnect the wire after starting. Regards, Dylan |
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Mark3 LifeTime Member
Age: 61 Zodiac: Joined: 13 Feb 2009 Posts: 4016 Location: Rainham Village, Essex.
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Posted: Thu Apr 22, 2021 9:23 Post subject: |
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Heater plug control unit (or timer relay as you put it) is behind the glove box, easy enough to swap over just unscrew it and unplug it and its a way better and quicker repair than *beep* around with a manual button, thats just a bodge
Turn the IGN on and unplug stiuff until you hear the heater plug relay clunk off and you've found it |
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isdyl22 Newbie
Age: 53 Zodiac: Joined: 05 Apr 2021 Posts: 7 Location: Woking
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Posted: Wed May 05, 2021 20:24 Post subject: |
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Hi - sorry for the slow reply but since my last post I found that the alternator had packed up so I've been messing around changing that. Amazingly the bottom bracket hole which is part of the front engine cover (time chain cover) had become an elongated slot, so I've changed that too. More involved than expected. I'll take a look behind the glove box tomorrow. Thanks. |
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isdyl22 Newbie
Age: 53 Zodiac: Joined: 05 Apr 2021 Posts: 7 Location: Woking
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Posted: Thu May 13, 2021 10:45 Post subject: |
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Well if anyone is interested, the issue seems to have been caused by the failed alternator. I'm surprised they were connected. Doesn't seem to have been due to low battery as it happened even after the battery was freshly charged. |
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isdyl22 Newbie
Age: 53 Zodiac: Joined: 05 Apr 2021 Posts: 7 Location: Woking
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Posted: Thu May 13, 2021 15:08 Post subject: |
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Oh sorry - ignore that previous post - the plugs are still staying on, and are likely the cause of the failed alternator! They are drawing a massive current and the revs actually raise slightly when I remove the small wire from the solenoid. Will have to look back at the timer thing. |
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emax LifeTime Member
Age: 67 Zodiac: Joined: 02 Aug 2007 Posts: 2277 Location: Purleigh
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Posted: Thu May 13, 2021 21:55 Post subject: |
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Hope the heater plug control unit solves the issue, nice to keep us updated. You will get there in the end, we always have to, being die hard paj techs |
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