diagnostics for the '87-94 glow plug system
for those with the newer glow plug system '87+ here is some more info from Haynes diesel tech book #10330
wiring harness check
engine OFF > remove wires from GP's > test continuity with your ohm meter between the test terminal (this is the one with that flat metal plate that folds/coils downward.) > repair any wires that are open.
you may need a new controller,but there are a couple more things to check before testing that.
check the ground for continuity.
you want 0 or a max of 1 ohms.
supply voltage test
with the engine & ignition OFF
there should be 10+ volts to the power supply terminal (the big red wire,which is hot all the time?)
recharge batteries,or repair this wire if less than 10 volts.
ignition switch voltage test.
ignition switch ON /engine and all accessories OFF > test the voltage between the ignition terminal and ground.
less than 8 volts or more?
if less than 8 volts,repair the wiring/ inspect-replace the fuseable link.
if more than 8 volts;
control function test
(which is likely where your trouble is.but hey,its best to check everything out first right. )
engine and switch OFF > connect test light to test terminal (the metal Z bar) and of course ground >
temps to time duration:
temp of control unit (F) - WTS (wait to start lite duration) - TL (test lite duration)
-20 / 7-15 WTS / 35-70 TL
0 / 7-12 WTS / 25- 60 TL
35 / 5-12 WTS / 15- 35 TL
70 / 3-5 WTS / 7-15 TL
105 / 1-3 WTS / 3-5 TL
140 / 1 or less WTS / 1-3 TL
if your duration's are correct,it's ok.if not,you need to replace it.
wait to start light lamp diagnoses
if the WTSL remains ON
unplug the connector at control unit.
turn ignition switch ON.
if the WTSL goes OFF,disconnect the ground cables to batteries and replace the control unit.
if the WTSL remains on,trace out and repair the wire to the indicator light.
if the WTSL doesn't turn on
unplug the connector at control unit.
connect a jumper wire from the harness side to ground.
turn ignition switch ON.
if the WTSL remains OFF,replace the bulb or trace out and repair the wire.
if the wait to start light flashes rapidly
happens when two or more GP's are burned out
test for continuity (or via the test light method as noted by Niles above) and replace as needed.
caution!!!
it is strongly advised by the masses to replace glow plugs with motorcraft (they are made by BERU in Germany) only.
motorcraft glow plugs (GP's) can be purchased online much more affordable than at your local ford stealership.
do not be tempted by other store/house brands.not only do they not last,many of them swell up becoming stuck in the engine head.often requiring head removal to remove them! there have also been reports of them swelling up,braking off,and cleaning out the top of pistons which leads to full engine reman or replacement.
do as you wish but,you have been warned!
need to save up for a set of beru's and thinking of buying a cheap set to get you by for now?
reconsider.try doing one these temporary starting aids instead;
use your block heater,or even just a blow dryer shot down the intake for 2 minutes will help start the engine right up if you can't wait for the block heater or it's not working either.
if your not by an e-outlet,then consider unplugging the gp harness and carry a gallon of gas with a rag.dampen the rag not enough to drip and hold it over the intake,the fumes are said to help start a diesel engine this way.
or last but not least,just disconnect the gp harness and use starting fluid (preferably while cranking the engine as you spray very short bursts to help it fire) until you can afford to buy a set of beru gp's online.
i would do any of the above before i even thought about screwing an off brand gp in my engine fwiw.
do as you wish but,you have been warned and informed of alternative temporary starting assist aids!
remember: if it's not a Beru,it just wont do!
for those with the newer glow plug system '87+ here is some more info from Haynes diesel tech book #10330
wiring harness check
engine OFF > remove wires from GP's > test continuity with your ohm meter between the test terminal (this is the one with that flat metal plate that folds/coils downward.) > repair any wires that are open.
you may need a new controller,but there are a couple more things to check before testing that.
check the ground for continuity.
you want 0 or a max of 1 ohms.
supply voltage test
with the engine & ignition OFF
there should be 10+ volts to the power supply terminal (the big red wire,which is hot all the time?)
recharge batteries,or repair this wire if less than 10 volts.
ignition switch voltage test.
ignition switch ON /engine and all accessories OFF > test the voltage between the ignition terminal and ground.
less than 8 volts or more?
if less than 8 volts,repair the wiring/ inspect-replace the fuseable link.
if more than 8 volts;
control function test
(which is likely where your trouble is.but hey,its best to check everything out first right. )
engine and switch OFF > connect test light to test terminal (the metal Z bar) and of course ground >
temps to time duration:
temp of control unit (F) - WTS (wait to start lite duration) - TL (test lite duration)
-20 / 7-15 WTS / 35-70 TL
0 / 7-12 WTS / 25- 60 TL
35 / 5-12 WTS / 15- 35 TL
70 / 3-5 WTS / 7-15 TL
105 / 1-3 WTS / 3-5 TL
140 / 1 or less WTS / 1-3 TL
if your duration's are correct,it's ok.if not,you need to replace it.
wait to start light lamp diagnoses
if the WTSL remains ON
unplug the connector at control unit.
turn ignition switch ON.
if the WTSL goes OFF,disconnect the ground cables to batteries and replace the control unit.
if the WTSL remains on,trace out and repair the wire to the indicator light.
if the WTSL doesn't turn on
unplug the connector at control unit.
connect a jumper wire from the harness side to ground.
turn ignition switch ON.
if the WTSL remains OFF,replace the bulb or trace out and repair the wire.
if the wait to start light flashes rapidly
happens when two or more GP's are burned out
test for continuity (or via the test light method as noted by Niles above) and replace as needed.
caution!!!
it is strongly advised by the masses to replace glow plugs with motorcraft (they are made by BERU in Germany) only.
motorcraft glow plugs (GP's) can be purchased online much more affordable than at your local ford stealership.
do not be tempted by other store/house brands.not only do they not last,many of them swell up becoming stuck in the engine head.often requiring head removal to remove them! there have also been reports of them swelling up,braking off,and cleaning out the top of pistons which leads to full engine reman or replacement.
do as you wish but,you have been warned!
need to save up for a set of beru's and thinking of buying a cheap set to get you by for now?
reconsider.try doing one these temporary starting aids instead;
use your block heater,or even just a blow dryer shot down the intake for 2 minutes will help start the engine right up if you can't wait for the block heater or it's not working either.
if your not by an e-outlet,then consider unplugging the gp harness and carry a gallon of gas with a rag.dampen the rag not enough to drip and hold it over the intake,the fumes are said to help start a diesel engine this way.
or last but not least,just disconnect the gp harness and use starting fluid (preferably while cranking the engine as you spray very short bursts to help it fire) until you can afford to buy a set of beru gp's online.
i would do any of the above before i even thought about screwing an off brand gp in my engine fwiw.
do as you wish but,you have been warned and informed of alternative temporary starting assist aids!
remember: if it's not a Beru,it just wont do!
