Sensor wiring

[johnfireball]

Hi all,
I,m working on the wiring for my Diahatsu Dnepr and have sorted everything bar a sensor which I believe changes the spill point depending on coolant temperature on the high pressure fuel pump.There is a sensor set into the thermostat housing which has two connections neither of which is an earth. When cold its resistance across the wires measures 1550 ohms when hot it measures 290 ohms. On the fuel pump there is a screw in component with two wires exiting neither of which is an earth and when cold or hot measure much the same resistance 650 ohms. I imagine the water sensor is connected live in series with one of the component connectors but cannot fathom why one of the component connections is not earthed. I am somewhat reluctant to experiment for fear of causing damage. Any electrical guru's out there who might have some ideas?
Thanks John.

[johnfireball]

Hi all,
Been doing some research on line and am now thinking that the unit on the pump has nothing to do with the engine temperature but is perhaps a sender unit for a rev counter. Will explore further.
John.

[Crazymanneil]

could well be rev counter. could also be cold start advance? my fiesta had a wax thermostat type thing that pulled a cable for cold star advance. it'll probably run without it if it is either of those anyway?

[Darren]

I don't think that it would be a rev counter probably cold engine advance, possibly increasing the idle speed with cold engine.

I wrote a lot about the various modules used on Bosch VE pumps. Your engine will have a Japanese manufactured licensed copy. Lots of different modules used but something on here may help.

http://wiki.obed.org.uk/index.php?title=Bosch_VE

What was the original application for the engine?
Do you have much of the original wiring loom?
Can you follow the wires from the components through the loom from the sensor and the mystery actuator?

I would expect the wiring to be live - temp sensor (switch) - actuator - earth or possibly live - actuator - temp switch - earth

[johnfireball]

Hi Darren etc,
I have investigated further following the piece of old loom I have. One of the connections on the temperature sensor is wired to earth as is one of the connections on the pump unit. This leaves me to think that they are not related. I unscrewed the sensor from the pump and it appears to be a magnetic coil pickup (not a solenoid) so I am further convinced its a rev counter sender. The engine is from a Daihatsu charade turbo diesel car which was fitted with a rev counter. The mystery temp sensor I am now thinking might have had something to do with air conditioning?
Thanks for input John.

[johnfireball]

Hi Darren,
Forgot to mention there is a vane pump run off the back of the alternator which increases turbo oil pressure and also generates vacume to power the brake servo and also increases idle speed when the engine is cold, but there seems to be no timing advancer or is it retarder. Anyhows engine starts on the button and I dont think I have a problem.
John.

[Darren]

Hello John,

Many Bosch VE type pumps dont have a cold engine advance unit. I think they were generally fitted to improve emissions to comply with regulations in the markets in which they were being sold.

Not heard of a tacho signal being taken from an IP sensor. Generally diesels use a engine speed sensor on the flywheel (when fitted for ABS/engine management purposes) or an output from the W terminal on the alternator.

[Crazymanneil]

Intriguing!

Darren makes good points that tacho is generally taken from somewhere else. Why go to the hassle of machining a boss into the fuel pump where there is easier ways to do it?

Wonder what it is now. Its almost would make you think of the sensor and toothed wheel setup in the electronic pumps like the VP37 but then there would need to be an electronic advance actuator. I am assuming the engine has no ECU (how wonderful that would be let me tell you!)

Did the car have any sort of "economy" warning on the dashboard? I remember one of these cars from when I was younger had one of these that turned red (practically if you tried to accelerate at all). The sensor could then be an injection quantity sensor??

Neil

[johnfireball]

Hi Crazy,
I never drove the car only removed the engine from it. It was a 1992 car, the last of the daihatsu charade turbo diesel models so it may well be as you say. Is there any way of checking its output without needing an sillyscope.
John.

[Crazymanneil]

Hmm hard to know without knowing what the sensor does. Did you try a normal multimeter across it on AC voltage measurement mode with engine running?

The economy light was on the instrument cluster from what I remember although may have just been on petrol cars.

Just interested now really. At least it runs for you.

Neil

[johnfireball]

Hi all,
Found out some more info by surfing, apparently the temperature sensor in the water jacket is connected to the glowplug relay so that even after the engine is started the plugs (I think) are powered on and off during the warm up to prevent smoking.Perhaps theres a resistance wire in the circuit somewhere. On the original wiring there was more than one connection wire to the plugs, so perhaps its a little more complex than I first believed. However I will wire it with a manual pushbutton and put up initially with the smokey warm up.
Thanks for input,
John.

[Darren]

Quite a few pre-ECU vehicles have an engine temp sensor which is connected to the glow plug relay and used to determine the length of the glow periods (pre and post start)

I sometimes add resistance to the sensor circuit to increase glow times to improve starting and cold running when fuelling with vegetable oil.

[johnfireball]

Hi Darren,
I found this website which explains all including my smokey startup. I'm now nearly sure the sensor on the fuel pump is for a taco and the water jacket temp sensor is for the glow plug relay. Thanks for all the help.
Regards John http://www.4crawler.com/Diesel/GlowPlug.shtml

[roodesign]

would this system work on another engine?..like my Kubota z482? I would like that auto feature to keep from burning out the g-plugs...this is the vw system in the previous link?

anyone tried it?

[smokyjoe]

Hi Roo and all,

An old Rabbit/Golf/Jetta ('78 to '92) glow plug relay module will work, be sure that the water temp sensor (they are M10X1 thread, Enco has cheap taps) you get is for the glow plug and not the temp guage- they have different resistances. Also there is a fast glow and slow glow. The fast glow is for higher current plugs as used in non-turbo cars and the slow-glow for turbo and older cars that run the plugs longer. It's better explained in the 4crawler link. Generally non-turbo '85 to '92 cars are the quick glow. Either module should work for you, the fast glow module supplies the same voltage (the plug's hot resistance determines the current) to the plugs as the slow just the timing is different, but the slow module used with the fast plugs could cause them to burn out sooner by leaving them on longer (a guesstimate based on my experience).

If you need a module or the temp sensor Clark's may have a couple of Rabbits, but please leave a few parts for me!

A question is, what is the REAL glow plug voltage supposed to be? I think that the glow plugs are designed to take into account wiring resistance losses, relay losses, battery droop, etc. etc. I've burned out VW plugs by connecting directly across a good 12 Volt battery for too long (15 seconds?)! Maybe it is wise to use the same wire guage and length as in the original application to be on the safe side. My Kubota engine came with the glow plugs and little else, but a friend has the same engine in a Kubota utility vehicle. I want to measure the glow plug voltage on his and be safe.

Have fun!
Brad

[johnfireball]

Hi Brad,
I did the same thing wiring one plug to the battery and burnt it out. It glowed white and melted. I would be interested in knowing the voltage mesured on your friends machine.
Thanks John.

[Nanko]

Rated voltage on the BOSCH glowplugs is 11 V.
I have some 15 seconds timers ( ex peugeot) they use environmental
temperature to set the glow time.( infact it varies the time the warning
lamp lights)
Voltage on the starter solenoid is used to interrupt preheating
If somebody likes to have one , pm

[johnfireball]

Hi all,
To whoever may be interested I have finally got a handle on the glowplug operation. I removed the injectors so I could see the tips of the heaters in the pre combustion chambers. The bus bar joining the heaters is connected to what I thought was a switch screwed into the cylinder head which I presumed was to prevent the plugs heating when the engine is hot, but I was mistaken, it is in fact a resistor which drops the power to the plugs for the warm up. So I wired up the plugs and powered them off one side of the resistor, they glowed cherry red in 5 secs. I then powered them off the other side of the resistor and they heated very slowly and just got hot(not red). I reckon the cold start procedure is 5 secs on full power then switch to low power for the warmup as long as necessary. I will wire it with a pushbutton for the quick 5 sec heat & a switch with warning light for the warm up. I am using a bike starter solenoid for the high power side and a 30amp relay for the low power. Would anyone know where I would get a 70amp fusible link wire for the high power side? While messing about I decided to clean the injectors and found one of them had a broken spring which would explain the excess smoke, so dropped them all down to the diesel shop for overhaul.
John.
John.

[Crazymanneil]

My audi A4 tdi has an 80 amp blade style fuse - bound to be able to get a 70 amp one? Its blade style but quite a bit bigger than a standard blade fuse.

Stuart was talking about bike wiring on another thread. Would be nice to use a breaker rather than a fuse possibly.

Neil

[Nanko]

In the CONRAD catalogue , chapter car HIFI : SINUS LIFE , breaker and blade type fuses , in 20 - 80 amp range

[Darren]

I use fuse holders like the one pictured below for glow plug. You can pick them up cheap from ebay - or I can supply, probably a bit cheaper. Got all kinds of automotive type electrical stuff to sell, and can get loads more, including a large range of glow plug relays - not got much of it up on my webshop yet.

[johnfireball]

Hi Darren.
Whats the physical size of that fuseholder and how much + postage to Dublin.It's what I'm looking for as I dont think the push on terminals are good enough to withstand the load.
Thanks John.

[Darren]

Sorry for the considerable delay getting back on this.....

Not including the mounting tabs 7cm x 2.5cm and it stands just over 2cm high.

Cost delivered to you £3.50

Best

Darren