6.5LT No Start, No Glow Plugs
 

I have looked @ hte no start list in the forum, but i will ask my question. I have a 1997 Chevy 3500 6.5L Turbo. I am currently not getting the glow plug curcuit to work.

Here is what i know so far. There is power to the relay. ON the 3 wire plug, i ahve 12V @ the red wire when the key is turned, i have ground @ the black wire, but i am not getting 12V from the ECU to turn the circuit on. The yellow wire is fine from the relay to the ECU. Therw is 12V to the ECU, and ground. I can't not connect to the ECU through the scan tool.

Some Backround. The truck ran great will last week. i was replacing the solonoid for the plow and cleaning up a ground on the passengers side fender. Once back together, the fuel and temp guage went crazy. turned the truck off, and checked the ground. The guages now work fine, and if the ground is removed they still work. think the ground is for the front headlight area. Also my heater doesn't work. Sometimes it works on high, but not all the time.

I have a feeling the ECU is bad, but am not sure how to properly test it, as i don't want to throw parts @ it.

Thank you for any help.

did you get 12v at the 2 big studs when you turn key on if not bad glow plug relay

no, i only get 12V @ one stud. But i am not geting the 12V from the computer on the yellow wire to tell the relay to turn on.

did you check 2 ECM and Glow plug fuses under hood

All fuses are good. The ECU is getting power, but i don;t think it's turning on.

do here glow relay click

the relay is not turning on, and the wait to start light is not comming on eather

sorry this didn't catch my eye check the fuse for the The OBD II connector is powered by the aux cig ligther circuit.

see the pics for diagnosing

Circuit Description

The glow plug system is used to assist in providing the heat required to begin combustion during engine starting at cold ambient temperatures. The glow plugs are heated before and during cranking, as well as during the engine operation. The PCM controls the glow plug ON times by monitoring coolant temperatures and glow plug voltage. This system check will check the glow plugs and the glow plug feed circuit coming from the relay.

Diagnostic Aids

If the glow plug relay is stuck in the ON position, check for proper operation of glow plugs. When glow plugs are commanded ON by the scan tool, an internal PCM timer protects the glow plugs from

damage by cycling them ON for 3 seconds and then OFF for 12 seconds. Most glow plug system failures are covered by DTC P0380. If no DTCs are stored, vehicle is hard to start and white smoke is present during cranking or after the vehicle is started. The most likely cause of failure is the glow plugs.

Test Description

Number(s) below refer to the number(s) on the diagnostic table.



1.This step will make sure OBD system check is performed.
2.This step will make sure there are no other DTCs stored that will affect the operation of the glow plug system.
3.This step will check each glow plug for an open.
4.This step will check each glow plug feed circuit for an open.

woody35. i will check those things when i tomorrow. i looked @ the 1st pic of the diag, and not sure if i can do that since i can't even access the ECU with an scan tool.

its going to be pretty hard to diagnose without one

yea, i know. every time i plug the scan tool in, i just get, "can't connect to the computer, try again"

Did the fuse for aux cig ligther circuit.

The OBD II connector is powered by the aux cig ligther circuit.
If fuse is blown scanner will not read the puter

here is a schematic also

got to check the wires running in and out of the puter for breaks

i will check what i can. It won't be till thursday till i ahve some time. thanks for the help so far

SO i get a few mins to look @ the truck. I checked the fuses for the acc port. i have power ther, it will charge a phone, yet still no link to the computer. the OBD2 port does have power.

jump direct off battery to glow plug sol.

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let me no if u need more info.

maybe code reader is bad

naw, the code reader is fine. i use it all the time. I sware this truck confuses the hell out of me

i ave no clue what do let me look thur my books and see if the don't work i will get back to you

thanks for all the help. i really don't want to take it to the dealer or shop cause i know i will get raped.

don't take to dealer they just going guess at it cost you lot money for getting no where

run a relay switch to sol ,to see if its good so u can test it manulywill let u no if sol. is good go from there.

ok, i will wire a switch up tomorrow. and let you guys know what happens

make sure you have power at pin 16 here site tell you pins


OBDII - On-Board Diagnostic's System - Does My Car Have OBD-II? The Connector and Communications.

if you don't have power at pin 16 code reader not going turn on

for thing it going to hard for code reader read codes for glow plugs cause time it get power up glow plugs shut off

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Should also say the that pin 16 don't come live in till key is on so code ready come live then buy that time glow plug light is off maybe that way you not getting any reading

ok, so i got an odd twist now. Went to test the relay today, and everythign was working. lights all came on, truck started and i can now scan the computer. It did stall a couple times on me, but it started right back up. SO i must have a bad connection somewhere or what not, i have no clue. who know when i tt will start acting up again.

So that was short lived. it's dead again. do you think it could be a ground issue somewhere? I am going to go over all the ground, and maybe add a few more.

check the + wire from driver side battery to the fuse box buy fire wall i have seen that wire being bad at the stud or loose

ok, i will check that wire. what confuses me is i have power to the whole truck.

think i might have found the problem. looks like the wiring harness on the pas side fell on the exhaust manifold. the wire are melted together. i need to fix that and see what happens.

so i know it's been a while, i had to step away for some time. So i have fixed all the broken wires, basically i replaced the whole glow plug circuit. Still nothing has changed.

What is all comes down to is the computer is not sending power to the relay to turn it on. I have power on the big stud, on the wiring clip i have power to the pink wire, and ground on the black, but no power on the yellow wire from the computer.

bad ecm?

that is what i am thinking, but would that cause it to randomly work and not work?

i had the same problems. i got a ECM from autozone for 94 bucks. Mine would run sometimes and sometimes wouldnt. i could tell when it would run by if the glow plug light came on. NO LIGHT NO RUN. is how mine was. the other problem i had was the plug going into the ECM closest to the glove box had a few loose wires. if i touched them it would die. Got that fixed and have had no problems since

so your problem was really both? bad ecm and loose wires?

Yep pretty much. I had to take some of the little wires out of the plug and smash the ends back shut si the would get a good conection

Well i spoke to soon. After i replaced my ECM i didnt have a single problem with my truck for 8 months. Now i am back to the same problem you are having and the same problem i started with. My ECM was under warranty so i took it back and got a brand new one. Still didnt fix it. Truck runs great when it starts. But if now glow plug liget no start and i also replaced the glow plug relay this weekend and starts sometimes and sometimes nothing.

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I have a few minutes I will give you a little history on my truck and my issues. I have a 1995 6.5TD. I got it because the old owner couldn’t get it running. The issue they had was if the glow plug light didn’t come on it wouldn’t start. Some days it would start and run fine and others it wouldn’t. I got the truck after they put a new LP, IP, Glow Plug relay, PMD. And so on they spend a ton of money at the local diesel shop and didn’t get too far. So I picked the truck up dirt cheap. I went over everything that was already done and cleaned all the grounds and still start sometimes others wouldn’t. I repaired wires and all kind of stuff like that. So I put a new ECM in it the truck started right up and didn’t have a single problem with it for 8 months. Now it is back to doing the same thing. The ECM was under warranty so I took it back and got a new one. After trying to start it I got a code for the glow plug relay so I replaced it and the truck started up and ran great. Well this morning it wouldn’t start again. The thing I noticed was when I turn the key if I don’t get the glow plug light the truck won’t start. And if I don’t get a glow plug like I can’t get any codes because it won’t read the computer. I am just as lost as Whitgit. So if you (whitgit) figure anything out let me know and I will do the same. It sounds like we have the same problem right to a TEE.

how about the other gauges on the dash do they still work when have no glow plug like

Yep all the other gauges work fine. I think it has to be a bad wire some where. At lunch i wiggles the wires on the drives side where they come thur the fire wall it it started right up. I dont know if this means thats where i shoudl start looking or if it is just one of the times it wants to start