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View Full Version : What causes the glow plug light on dash to not work? (1982 245 D24)


chad1966
03-12-2013, 11:25 AM
(1982 245 D24)
What causes the glow plug light on dash to not work and the glow plugs?
It happened last week out of the blue.
I visually inspected the wiring and nothing seems to have broke or fallen off. Yesterday the GP light came on 1 time just randomly after coming out from the store midday.
I put a new #13 fuse in.
I believe there is a GP temp sensor at the back of the head.
Is it the female terminal that sits roughly in the middle of the rear timing belt? If it is getting a bad connection would that signal that the engine is warm/hot to not turn on the GP?
It will start in the AM but only after I give it a little fuel for about 5 seconds and than it will idle on its own.
This is defiantly not what has been the case from the time that I bought the car.
It usually starts right up to an idle.
The only thing that I have changed is that I am currently just about through my first tank of B50.
I dont think that that should affect the GP though.
Any help is appreciated. Thanks.

RedArrow
03-12-2013, 01:19 PM
You probably checked it already... there is a (I think 80A) strip fuse in the glow plug relay.
I used B99 in my 740TD a lot without any issues. I never noticed any difference at all when I switched back and forth to/from B99, B50, B5 or regular diesel, except for the smell of course. I don`t think your B50 fuel should affect the glow system (same is not true on the filters though) but the pro d24t nuts will share their opinion as well. Currently (and all Winter long) I used B30 in mine as it is `Winter` but I will get back to B99 by April. I *never* had any starting or idling issues related to biodiesel fuel (not in cold temps either).
Btw, long ago in our 244GLE d24 I installed a small black pushbutton switch on the dashboard right next to the instrument cluster`s light adjuster switch. it worked as a protector against car-theft: :) the car would not start without the glowplugs being on. I would love to have a manually operated glow plug system in mine so I could turn it on/off myself, this way avoiding headache and issues of them staying on for too long, or what`s worse : all times... until... :(
I mention here that I remember I also had the glow plug light come up unexpectedly, a few times while driving in the past but that time I had my ignition switch going downhill (thanks to some oily residue inside of it that got in by the key and covered everything in there resulting my ignition switch to not let me start the car at all). Any issues with that ign switch maybe? Good luck. I hope you sort it out soon!

chad1966
03-16-2013, 07:20 PM
Ok I am convinced that my glow plugs not working than now working all of a sudden has a lot to do with the coolant and specifically the sensor located at the back of the head. I noticed I was low on fluid a few days ago so I topped her off. Their must of been air bubbles or just air trapped some where because it took a day for them to start working. They now work with all the time. I will keep an eye the coolant level.

RedArrow
03-16-2013, 09:51 PM
Ok I am convinced that my glow plugs not working than now working all of a sudden has a lot to do with the coolant ... I will keep an eye the coolant level.

ALWAYS DO. Wouldn`t it be very nice to know about our coolant level *while driving*?! I heard that 850s have a coolant level sensor. That would be a great thing to somehow adopt for our diesels.
On a bad day @Togwotee Pass, Wyoming (-13C=8.6F luckily very cold; Elevation: 9,659' =2,944 m), I quickly lost a Gallon (~4Liter) of coolant thanks to the cap of the expansion tank: it was not tightened enough. Having a coolant level sensor wouldn`t let that dangerous thing happen. I mean, it would have alerted me much earlier in a critical situation like that. There is probably some kind of compensator built into the temp gauge too because the 740`s coolant temp gauge is somewhat `slow` ... so by the time I got the news, the car was already overheating unfortunately. Me too! I`d love the idea of some type of level sensors. Till then, keep all your eyes & 6th sense strictly on your slow-motion (then `jumping`) coolant temp gauge. :(

ngoma
03-16-2013, 11:13 PM
chad1966, hard to believe low coolant was rendering GPs inop. Thermo sensor should be giving simple resistance value to GP controller. Unplugging sensor gives signal of max resistance, fooling the GP controller into thinking it's very cold, needing max GP time. Hot thermo sensor should give low resistance signal to GP controller, telling it no need for GP. How would low coolant level cause this?

I do strongly agree on the value of a low coolant warning lamp, would help eliminate a major factor in premature death for these engines, I plan to install on my car, here is a helpful description:

Loss of Coolant Sensor for Volvo 740/940 Cars:
http://www.brickboard.com/FAQ/700-900/Cooling.htm#LossofCoolantSensorforVolvo740940Cars

chad1966
03-17-2013, 07:14 AM
I don't know for a fact and I have not yet diagnosed my GP situation. It probably was just a coincidence but the only thing I did different from when they stopped working was add coolant, and that's when they started working again. They also would work before I added coolant after a long drive when the car was hot. This is my first Volvo and diesel so everything little problem that happens is a learning experience for me.

v8volvo
03-17-2013, 10:00 AM
Early 200 series cars up until halfway through model year 1984 use a different glow control system than the 700 series: 700 series has one large GP relay under the hood that serves as the switching relay and the timer/controller, all in one unit, while 200 series uses two separate relays -- one under the hood, which is a simple "dumb" relay that just switches power to the plugs on and off on command, and a second relay under the dash (Volvo's name for it IIRC is "blocking relay") which is the one that receives the temp signal from the sender in the head and controls whether the underhood relay operates and for how long. The very last run of 240 Diesels imported here (sold as 1984 models, but on dealer lots during model year 1985 and displaying a variety of changes that were in evidence on gasser models badged as '85s, therefore in reality a "1984.5" model :rolleyes:) featured a much-reconfigured electrical system featuring the same glow control arrangement and single large underhood "combination relay" used on the 700 series.

The blocking (i.e. control) relay on the earlier 200 series is a yellow rectangular relay hanging under the steering column, and given the description of your symptoms an issue with it or the connections to it would be a likely suspect as far as a cause of erratic glow plug light/glow system function.... might want to start by looking there, if it's hanging half out of its socket or has corroded contacts, etc, could give you an easy solution.