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Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 25350
Experience:  14 years GM dealer Technician.
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Chevrolet Suburban K2500 4x4: i have a 95 chevy 6.5 diesel

Customer Question

i have a 95 chevy 6.5 diesel suburban. It recently died and i can't figure out the problem. i replaced the fuel filter and pump. checked the glow plug connections and they seem to be tight. however now will start (sometimes) and run for about 30 seconds - 1 min and then die. sometimes the glow plug light comes on in the dash and sometimes it doesn't. every time i have got it to start the light has been on. however now it won't come back on and won't start. I took the batteries out and have them charging. I'm thinking maybe its the pad? or maybe the glow plugs need replaced? or maybe i have a bad connection to one of the glow plugs. idk.. any ideas?? thanks!
Submitted: 1 year ago.
Category: Chevy
Expert:  Pete replied 1 year ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
One very common component to cause this issue here is the glow plug relay itself.It can act up intermittently and allow the glow plugs to operate in some cases and not operate causing a no start issue.When the glow plugs are not operating due to the relay acting up the engine will start with compression build up but may only run shortly and stall out.
I would have the glow plug signal tested to see if the relay is the cause here and the relay replaced as needed.
Thanks Pete
Customer: replied 1 year ago.
I've tested the relay myself with a light tester. It gets power all the way though and past the fusable links. I can hear it click when I turn the key. However when I try to test the plugs themselves l I turn the key and walk over th test the connect and nothing happens. Idk if the fusable link to the glow plugs are faulty or if I'm just not getting there soon enough. So you don't think it's the pmd? A lot of the reviews I've read online seem to point in that direction. When this problem started I was just driving the truck and it die on me. I had had this happen to me on several other occasions but it would start back up. Sometimes it would start up right away and other times I would have to wait a minute or two. But like I said I replaced the fuel pump and the fuel filter. Still no luck so I moved to the ignition system. Sometime the plugs would come on and it would start and run for a little bit, but now they won't come on. So I pulled the battles and have them charging thinking maybe there's not enough juice to fire the plugs. Thanks
Expert:  Pete replied 1 year ago.
Have you had the electronic ignition switch tested at all?
Customer: replied 1 year ago.
No, I don't know what or where that is. Let me look it up.
Expert:  Pete replied 1 year ago.
Ok test and see if this electronic ignition switch is failing to send the correct voltage signals when the fault occurs.I have seen this switch fail before in the past and had to replace it.Let me know what you come up with here.
Thanks Pete
Customer: replied 1 year ago.
is it the same as the gas version??
Expert:  Pete replied 1 year ago.
Below is a link to the diagram from the electronic ignition switch.The power feeds coming in from the switch to the fuses.You can test at these fuses when the fault occurs and if none of the fuses have power when this occurs this indicates the switch at fault needing replaced.
Thanks Pete
Customer: replied 1 year ago.
ok, well just to be clear. all the other lights on the dash work. the glow plug light just isn't coming on. i checked all the fuses and they were good but i didn't check to see if they are getting power. haven't got that link yet... thanks
Expert:  Pete replied 1 year ago.
You have to copy and paste the link above into a new web tab to view it.Let me know if these fuses have power when this fault occurs.
Thanks Pete
Customer: replied 1 year ago.
that's fine. there just isn't a link. could you send it again??
Expert:  Pete replied 1 year ago.
https://www.dropbox.com/s/0d90s60jgln2oon/2015-06-05%2012.22.33.gif?dl=0
Customer: replied 1 year ago.
thanks
Expert:  Pete replied 1 year ago.
Your welcome
Customer: replied 1 year ago.
Ok, I got into the ignition switch. When the key is off my test light lights up on the red/white striped and the red one. When the key is on they all light up except the yellow one. Which according to the diagram is the "crank". I got tested the 10 amp fuse in the box under the hood and it is good but not getting any power not matter if the key is on or off.
Customer: replied 1 year ago.
The light does come on when you try to start it but there's still no power to the fuse under the hood.
Customer: replied 1 year ago.
so, it seems there is a problem somewhere between the ignition switch and the fuse under the hood. Is that a safe assumption??
Expert:  Pete replied 1 year ago.
I apologize for the delay as I was off line the last few days.
Try holding the key in the crank position like your trying to start the vehicle and test the crank wire,this is when it should have voltage.If it still does not have voltage this indicates a fault between the fuse and ignition switch or if there is no voltage out of the ignition switch itself on this wire when held in the crank position this indicates the electronic ignition switch itself is at fault needing replaced.
Thanks Pete
Customer: replied 1 year ago.
Hi, it does light up when you turn the key as if you were starting the truck. How ever when I have someone turn the key as if you were starting the truck there is no power at the fuse under the hood. All the other fuses have power but there's no power to the fuse that runs the glow plugs.
Customer: replied 1 year ago.
The fuse looks fine. No sign of burning or anything.
Expert:  Pete replied 1 year ago.
Did you test the fuse that runs the glow plugs with the first time you turned on the key or had the key been turned on a few times recently before you tested the glow plug fuse?
Customer: replied 1 year ago.
Been turned a few times recently, also some times the glow plug light will come on for a slight second on the dash. It's like it tries to come on and something is shutting it off right away.
Customer: replied 1 year ago.
This only happens after it's been sitting for a while. Like over night. After that the light won't come on at all.
Expert:  Pete replied 1 year ago.
Is this the 20 amp glow plug fuse or the 10 amp glow plug fuse that doesn't have power?
Customer: replied 1 year ago.
The 10 amp
Customer: replied 1 year ago.
Is there 2 different ones??
Expert:  Pete replied 1 year ago.
My data shows a 20 amp fuse which is fed power direct from the electronic ignition switch then a 10 amp fuse that only has power when the glow plug relay is engaged.So the glow plugs will come on briefly with a cold engine then turn off which is when the 10 amp fuse will have no power when the glow plugs are turned off.The 10 amp fuse will have power with the first time you turn on the key for the day for a few seconds to heat up the glow plugs but after this it may only have power briefly or not at all when you turn on the key.The 20 amp will have power at all times with the key on.
My info is not showing where the 20 amp is located,it may be in the harness from the ignition switch itself.
But with what is occurring here this almost sounds like the PCM (engine computer) itself may be the cause needing replaced.It commands the glow plug relay on as well as other components and can cause the stalling and no start issue here.
Customer: replied 1 year ago.
Ok, is the pcm different then the pmd? I've heard of that going out and showing the same symptoms.
Expert:  Pete replied 1 year ago.
The pmd is a driver control module on the injection pump which is also common to fail and cause fuel issues here.If you have not had the fuel system tested this needs done to see if the pmd or injection pump is at fault.This would need done by a diesel repair facility that has the special test equipment to do this testing.
The PCM is the electrical computer in the vehicle that controls and monitors the engine and some transmission components.It can be common to fail as well.
If the fuel system tests fine then I suspect the PCM is the cause needing replaced.The PCM is located behind the glove box on the passenger side of the vehicle.
Thanks Pete
Customer: replied 1 year ago.
Ok I'll check it out. Couple more questions. If I had the corect computer would it tell me the codes? I might have access to one. Also, do you think this could be a grounding issue? Because I haven't checked or cleaned any of my grounds. Thanks
Expert:  Pete replied 1 year ago.
It is possible it is a grounding issue with a loss of ground to the computers or engine components.Check and make sure the grounds on the back of the cylinder heads are clean and tight as well as the battery ground cable at the battery and to where it runs and connects to.
If you had access to a code reader that will work on this model here this would help in some cases to diagnose the fault.The older models like this here didn't set fault codes all of the time for no start issues like this here though.
Thanks Pete
Customer: replied 1 year ago.
Hey, so I worked on it again yesterday. I had a mechanic look at it as well. I check all the grounds and they seem to be ok. When I first got in the truck and turned the key the glow light would flicker but not come on solid. I waited a minute or two and turned it again and the glow light came on solid and stayed so I start it and it started right up. It ran smooth with no knocks or misses. Perfect. It died after about 30 seconds. When it dies it's just like if I were to turn the key and shut it off. We waited about 30-45 mins and I went to start it again. This time the lights stayed on solid the first time I turned the key. Started right up and my mechanic friend had me give it gas. I kept it at around 1500 rpms and it ran for about 2 minutes. Which is the longest I've had it run since it broke down. It died the same way as before. My friend thinks it's the crank shaft sensor. He thinks it's heating up and failing. Took a look at the sensor and it needs cleaned up really bad. Oil, dirt and it's a mess it that area. Also, after it dies if you try to start it The RPM gauge doesn't move at all. He said it should normally flicker at the bottom because the motor is turning over. Anyways, I don't think it's a gounding or a fuse issue at this point. I'm not sure about the pcm or the pmd. But I think they are both getting power and if they were the problem wouldn't they just keep the truck from starting all together? If it is a sensor issue which seems like a safe assumption I think the crank shaft sensor could definitely be the culprit. Any thoughts?? Thanks
Customer: replied 1 year ago.
Oh also, I couldn't get scanner just yet. But we are going to work on it again on Saturday and he is going to bring one. Thanks
Expert:  Pete replied 1 year ago.
Crank sensor failure is common so this is a definite possibility here.If this has not been replaced at all at any point in time on your vehicle I would replace it.Even if it doesn't correct the fault the age of this sensor will usually cause it to fail at some point.
If this does not correct the fault here let me know.
Thanks Pete
Customer: replied 1 year ago.
Hey, is there a trick to removing this sensor?? From the looks of it, is should just pop out. It only has one bolt, which I removed, however it's solid as a rock... It wiggles a bit but when I go to pull on it, it won't budge. There was a metal tab at the top where the bolt was that broke and half of the wires have broke with me trying to pull it out of the hole... What am I doing wrong?? Thanks
Customer: replied 1 year ago.
Hey, finally got it done. Disregard the last message. However, it didn't change anything. I finally got my hands on a scanner today as well. I'll up load the pics of the codes. Tried to look them up but I haven't had any luck so far. Let me know what you think. thanks.
Customer: replied 1 year ago.
Oh, and when you turn the key to start the truck, the "crank" switches to yes on the scanner. Fyi
Expert:  Pete replied 1 year ago.
The code you have looks to be an air bag fault code.Are there any other codes set at all?
Customer: replied 1 year ago.
Not that I could see. Every other option on the scanner it just reads no Communication.
Expert:  Pete replied 1 year ago.
O.k.,this is a difficult fault for me to be able to locate myself here.I will have to see if anyone else here can help more on this.
I will have to open this question up for others here to see if they can assist further on this as someone else here may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.
Thanks Pete

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