Do you have access to an amp clamp to check amps going to the glow plugs. Remove the oil temp sender which is on the back of the hi psi oil pump reservior 2 wires. This will make the relay run longer. Then hook clamp over the 2 brown wires on glowplug relay should have about 175 amps if its working right. I have also seen the fuel heater inside the fuel filter housing go bad as well. Might check all the fuses as well incase the fuel heater fuse is blown.
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Since some of your starting problem can be when you need the glowplug timer to work. There is a power relay which supplies power to the glowplug timer. After the engine warms up, the timer has little to do with starting.
You could also need new, clean glowplugs. When you do need the glowplugs to work, they can only get power for a fraction of the time that the timer works. If the glowplugs are worn or dirty, the glowplugs may not heat sufficiently to ignite the diesel fuel.
With a Diesel there are additional parts that you have which affect the Cold start. There is a timer between the glowplugs and the Power relay on the start circuit. The timer cycles the glowplugs off/on for a variable time period. The more cold, the longer the cycle period. Glowplugs go bad. You remove them like sparkplugs. Testing them is a matter of comparison. When power is applied they can melt, so test with care. Hook battery jump cables to each glowplug taking care to attach one lead to the base (avoiding the threads) and then briefly touch the top of the glowplug. The quicker the plug glows, the better it is. The darker, the worse it is. But the timer must provide the juice to the glowplug for it to work. A bad timer will not properly heat the glowplugs. The timer must get its' power from the Power relay. So you can have acceptable glowplugs, and a bad timer. Ultimately once the engine cylinders have run hot enough, a Diesel fires by compression and not by spark as a gas motor does. That is why once you have a hot diesel, it will start freely. It is why I explained the needs of a Cold Diesel engine and I hope this helps you.
If this is a diesel, the glowplugs are in the heads similar to how sparkplugs are installed.
You should first check several other parts. The glowplugs get their power from a Timer. The Timer sometimes is combined with a power relay or the power relay is separate. The power relay is turned on by a signal from the Ignition switch.
So if the Timer, Power Relay, or power feed off the Ignition switch, is defective, the glowplugs will not work.
Check one of the wires to the glowplugs with a Voltmeter. The Timer will send several pulses to the glowplugs and then need to cool off.
The glowplugs only work for a few minutes for the initial start.
If the above parts are good, then check the glowplugs by removing and using battery jumper cables.
Clamp one to the base of the glowplug avoiding the threads, then briefly touch the top of the glowplug with the other polarity jumper.
Caution--you can melt them. Just observe if one stays dark longer than another. A dark glowplug is bad, a bright glowplug is good. Its all relative.
This is not to hard to solve. The outside airtemp determines how long the Glowplug timer works for absolute cold starts. Starting a warm engine is affected by underhood temps.
The Timer Relay will pulse power to the glowplugs. If the glowplugs are good, it is enough to preheat the cylinder for firing.
To tell if a glowplug is good is a matter of comparision between a new glowplug and a worn glowplug. YOU CAN MELT A GLOWPLUG WITH THIS TEST, but you remove the glowplugs, get a set of battery jumper cables and place one jumper to the base of the glowplug USING CARE not to ruin the threads on the glowplug.
You do not want to arc the spark on the glowplug threads. You want your fixed jumper connector locked on the base of the glowplug. The other battery cable jumper is touched to the top of the glowplug where the arcing occurs. This will not hurt the contact point if done properly.
You compare the "glow" of the old glowplug to the "glow" of the new glowplug. Bad glowplugs stay dark or operate at a darker color.
The Timer Relay gives you pulses and that is all the glowplugs get to heat up. This is what you simulate in your test. If a glowplug operates in a dull or dark condition, it is bad and throw it away. You want all glowplugs to readily light up when power is applied.
The other 2 parts to the system are the Timer Relay and the Power Relay. The timer gets its power from the Power Relay and the Power Relay is like a starter solenoid. The Power relay gets a tickler charge when the keyswitch is held to Start.
There are sometimes extreme cold Timers that hold the power longer tothe glowplugs. I do not have the Specs to tell you if your Timer is kicking out to soon.
I hope my solution helps. I have told you how to test your glowplugs. The timers are affected by air temperature and that makes it difficult to say if it is working long enough. If you know the glowplugs are good, and the timer shuts off before the glowplugs heat up, then you need a new or different type of timer.
Hello, The diesel engine relies on Glowplugs for the first start in the Morning or a cold start at anytime.
The Glowplugs themselves can be bad, but there is a Timer which determines how long the Glowplugs will stay on. Before the Timer is a Glowplug Relay which gives the Timer its power to operate. The Ignition switch provides power to the Glowplug Relay.
You disconnect a Glowplug wire, put on a test instrument (either a testlight or Voltmeter) and look to see what happens when you initiate a start. If the testlight lights and cycles a few times like a pulse, then the power supply is good. If not inspect the Timer and Glowplug Relay for continuity
If all the pulses seem to reach the Glowplugs, then most likely the Glowplugs are worn out. Test by removing then and connecting battery jumpers. Briefly touch the top terminal of the Glowplug with the Hot cable after grounding the negative cable on the base of the Glowplug, avoiding the threads.
You can melt a Glowplug. But if you find the Glowplug staying dark, then it is bad. Do this for all the Glowplugs and replace the bad ones. Remember the Glowplug only has the amount of time the Timer gives it to work. So if a few pulses do not make it Glow, then replace it. This should fix you up.
Hello, Most likely your Glowplug Relay is bad, and it supplies power to the Glowplug Timer which also may be bad.
Just follow the wires that are on the Glowplugs up to the Glowplug timer. Use a Voltmeter and check if the power wire that goes into this Timer has fire when the Ignition is turned to the RUN position. If there is fire going into the Timer from the power Relay, pull off one of the Glowplug wires and ground 1 end of a testlight and put the other end on the Glowplug wire.
The Timer itself will kill the power after a predetermined time based on Temperature. The colder the engine, the longer the Glowplugs stay lit. If you have power reaching the Glowplug, your power Relay is fine. You just have to observe how quick the Timer stays on.
The Glowplugs only have 1 or 2 chances to do their job at the Start-up. They are needed to make a Diesel start cold. Cold meaning at outside AIR temperature, and engine block temperature. There should be clicks under the hood and the lights should flicker in rhythm to the clicks if the Timer is working.
If you find that both the Timer and Power Relay are working, the Glowplugs need to be tested. They come out like sparkplugs. But you test them either on a special machine or use battery jumper cables. To test, hook one battery cable to the Glowplug base, avoiding the thread. Then take the other cable and arc it on the top of the Glowplug.
Caution, you can melt the Glowplug. If you get a bright glow, the Glowplug is good. If the Glowplug is dark or very slow to glow, it is bad. This should be all you need. Would appreciate a note after you fix it.
Okay, If this noise happens when you turn the Key to start, your Starter Relay is bad. Now the other possibility is the Glowplug Timer. When you start a Diesel there is a pause in the initial cold start. You turn the Igniition Key to Run, then let the Glowplug Timer cycle. This cycle sound will be a series of clicks which also may cause the lights to dim.
The glowplugs absolutely must warm up to start a cold diesel engine. There should be a light on the dash which either goes off when the glowplugs are ready or a light will turn on when they are ready. It is only after that activity that you will turn the Key to Start.
Since Diesels take more power to Start, there are 2 batteries. As with a single battery system, every connection must be clean. If the Glow-plug Timer is working and you only get clicks by turning your Key to Start, check the things I said earlier. Your Starter Relay and the big cable connections.
If after all of that, the engine will not turn over and only clicks, jump the Starter Relay with 1 cable from a jumper cable set from the Positive Battery cable post to the Starter Relay on the Starter wire connector. Make sure the truck is in Park or Neutral. If the Starter jumper cable sparks and the Starter does not turn, the Starter is bad. If the Starter spins it confirms the Relay is bad.
I hope my Solution gets you going and that you consider this helpful.
The timer goes between the glowplugs and the Relay. When you turn on your Key it powers the Relay and the Relay sends power to the Timer. The Timer decides how cold your engine is and regulates the length of time or number of cycles you need to heat the Glowplugs.
If your dashlight has not burned out, there should be a Ready light or indicator that will tell you when to Start the engine. Either the light will stay on until it is ready to start or the light will come on after it is ready. Depends on the setup.
Now I have heard of a truckers trick which is to activate the Key twice. Let the timer cycle twice and then start the engine. It worked for me. Then I bought the parts I needed.
You do need to determine if your problem is fuel or glowplugs. At least with the glowplug timer you should hear clicking and should see the domelights or dashlights flicker to match each click. So you have a visual and audible way to test them.
I hope you find my solution very helpful in diagnosing the problem with your truck.
Its either one of 2 things. A shorted glowplug is backfeeding and shutting off the timer or the timer is bad. You should start by removing the glowplugs and testing them.
The glowplugs can melt with this test so don't overdo it. Use a set of battery jumper cables and put the NEG on the metal case without damaging the threads. Then take the POS cable and touch the top of the glowplug. Its a matter of comparision. A dark glowplug is cold or dead. When you get a good one you will see an intense glow. Replace the bad ones.
After reinstalling the glowplugs try starting your car. If it still does not work well trace all of the glowplug wires up to a timer box. There should be a Power source going into the Timer. Measure the Voltage going to the Timer. If it is less than Battery Voltage follow the Power wire to a Relay. The Relay may be in the blackbox full of Relays under the hood or independently hung next to the Timer. Sometimes thoughtful Engineers put labels under the lid for each component. Check the plugin sockets for corrosion or replace the Relay for the glowplug Timer.
If you had battery Voltage at the Timer most likely the Timer is bad. The Timer should keep your glowplugs on longer the colder the outside temperature is. The exception is a warm engine. Good luck on your repair. I hope you find my solution very helpful.