Chevy

Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

Chevy

Having electrical issue with lb7

Customer Question
Having electrical issue with lb7
Submitted: 2 years ago.Category: Chevy
Ask Your Own Chevy Question
Customer reply replied 2 years ago
03 lb7 has major intermittent electrical issue. p0202 0203 0205 0208 2149. Things I have done. Replaced whole top harness,ficm,pigtailes. Checked all wire nuts multiple times. I replaced injectors on my own and when I started Truck straight into limp mode. Pulled both valve covers twice checking nuts and wires finding nothing. Went through whole top harness and couldn't find any chaffing in wires. Still limp mode. Came out next day without doing anything else to it and it starts right up runs great for 2 weeks then problem again. Cleared codes and it runs again for few days. Sometimes it goes 1 day and it has went up to 6 months without doing it. Got tired of messing with it so I replaced top harness,ficm,pigtails,cleaned all electrical connectors and still same thing. I believe the only thing left is internal injector short. I ohmd out injector through pigtail and they are fine. As soon as I start it shuts down whole bank so I can't narrow it down
Answered in 46 minutes by:
8/24/2015
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29,591
Experience: GM Grand Master Technician 2007. 14 years experience.
Verified

Hi there, I am Cam. Can I ask if you had the orientation of the engine correct? On the druramax, Drivers side is even, 2-4-6-8 and passengers side os odd, 1-3-5-7. Is this what you expected and did you change all or just the effected ones?

Ask Your Own Chevy Question
Customer reply replied 2 years ago
I replaced all injectors bc of smoke at idle problem. After I changed all injectors truck started in limp mode with codes listed. But is extremely intermittent and have replaced ficm,top harness,pigtails and cleaned all wiring plugs
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

OK, when you say the top harness and pigtails, you mean the top engine harness and the pigtails that go to the injectors under the valve covers?

Ask Your Own Chevy Question
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

This only starter after replacing the injectors or did this start before replacing the injectors?

Ask Your Own Chevy Question
Customer reply replied 2 years ago
Only after
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

Ok, so to make sure I understand completely, you replaced the injectors, this started, you replaced the rest and it remained?

Ask Your Own Chevy Question
Customer reply replied 2 years ago
exactly
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

Ok, so one of the injectors, 2 3 5 or 8 is causing this. It has a fault inside and when it, the FICM detects one injector out or spec, it disables the group of injectors, in this case, 2 3 5 and 8. Unless it shows you a P020(2,3,5,8), its going to take testing each injector when the issue happens to know which to replace.

Ask Your Own Chevy Question
Customer reply replied 2 years ago
That's why I'm here ! Lol. I ohmed them all and they are all in spec from pigtail down to injector. How do I narrow down the bad one ? That's really the reason I contacted you but had to give the whole story
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

Understood. IF all of these were the EXACT same resistance, and you were using a quality meter with the leads zeroed out, then you would have to do what I would, pick a bank, replace the 2 and see which is does. Beyond what you have done, there is nothing special about testing these. They run on 93 volts from the FICM so we cannot simply apply voltage to see. I know this is not what you want, but the fact of the matter is that your diagnosis is spot on so far.

Ask Your Own Chevy Question
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

Were these GM injectors or aftermarket injectors?

Ask Your Own Chevy Question
Customer reply replied 2 years ago
Bosch reman
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

Exactly what resistance did you get for each injector?

Ask Your Own Chevy Question
Customer reply replied 2 years ago
05
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

And that is right in the middle of the spec. IT is 0.3 to 0.8 ohms. Did you zero the meter before testing?

Ask Your Own Chevy Question
Customer reply replied 2 years ago
I payed an arm and a leg for this multi meter. It self zeros it says. Is there not a way to unhook each of 4 trouble injectors one by one till it starts and doesn't throw those short codes
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

Ok, self zeros, that must be a good one. Sorry no. The FICM is not that advanced. It works in groups. While it controls each injector individually, if one goes out of spec, it disables the group. Attached is the diagnostic chart for this.

Ask Your Own Chevy Question
Customer reply replied 2 years ago
I have to just start replacing injectors till it quits ?
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

Unfortunately, yes. WE know its one of four, so myself I would Contact the supplier and explain to them what is happening. Then replace 2 as the time to get under each valve cover makes it harder to justify going in twice, unless you happen to get the bad injector straight away. However, I would get this engine really hot then test each injector again to see if you still only get 0.5 ohms.

Ask Your Own Chevy Question
Customer reply replied 2 years ago
Warmed up as good as possible on 4 cylinders then checked ohms. They all stayed between 4-5 accept cylinder number 2. It would go 34543 then stay at 3 for a sec then dropped to 2 for about a sec then started jumping between 2-5
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

I think that is enough of a reason to replace it. Getting an inconsistent reading and one that does drop below spec points to it as being faulty. Replace that injector.

Ask Your Own Chevy Question
Customer reply replied 2 years ago
Is there any way the short could be between ecm and top harness plugs and cause injector short?
Chevy Mechanic: GM Tech (Cam), Chevy Technician replied 2 years ago

The short and the wiring does not pass through those 2 large connectors, rather it goes straight from the FICM to the injectors. Everything you tested and the codes suggest it's a bad #2 injector.

Ask Your Own Chevy Question
Customer reply replied 2 years ago
Hey man. I got new solenoid for 2 injectors on driver side. 2and 8 replaced those and number 6 injector. Now I can't get it to start. Primed it for hours. Primer getting hard. I do notice that when it's cranking white smoke rolling out of exhaust. What could it be and how do I diagnose. Won't start to see if injector short codes are gone
Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29,591
29,591 Satisfied Customers
Experience: GM Grand Master Technician 2007. 14 years experience.

GM Tech (Cam) is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money.

Todd LRochester NY

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

GM Tech (Cam)

GM Tech (Cam)

Chevy Technician

29,591 satisfied customers

GM Grand Master Technician 2007. 14 years experience.

Gary

Gary

Chevy Technician

9,196 satisfied customers

15 years GM master tech

Tim&#039;s Auto Repair

Tim's Auto Repair

mechanic

8,847 satisfied customers

Have owned a repair shop for 25 yrs.

Dave Nova

Dave Nova

Chevrolet Technician

7,092 satisfied customers

ASE Master Certification. GM World Class Certification

John

John

Master A.S.E Automotive technician

4,071 satisfied customers

A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician

Don - Mo Lurch

Don - Mo Lurch

Auto Mech / Electronics

2,900 satisfied customers

Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.

Ron Z.

Ron Z.

- Chevy Tech -

2,682 satisfied customers

18+yrs experience. State Inspector and Chevy Diagnostics

< Previous | Next >

Related Chevy Questions
Engine makes a noise like a spark knock or an exhaust leak
Engine makes a noise like a spark knock or an exhaust leak from the right side of the engine during acceleration, this doenst happen all the time but it seems to run better when it doesnt make the noi… read more
Dodge expert
Dodge expert
ASE MASTER TECH, REPAIR FACILITY OWNER
High School or GED
3,636 satisfied customers
Replaced both 02 sensor on secondary exhaust 8 coil packs
Replaced both 02 sensor on secondary exhaust 8 coil packs spark plus ,mass air flow sensor spark plug wires ,purge valve and i still have code 300 and 138 will show up every now and then runs very rou… read more
roy
roy
Associate Degree
3 satisfied customers
I need to replace exhaust manifolds on a 1970 Chevy 1/2 tin
I need to replace exhaust manifolds on a 1970 Chevy 1/2 tin stock 450 2 barrel Automatic what would be the best manifold for fuel economy… read more
camerontech
camerontech
20 year experience diagnostic technician
class a
544 satisfied customers
Where is the Exhaust Cam Position Actuator Solenoid located
Where is the Exhaust Cam Position Actuator Solenoid located on 93 GMC Serra Trunk ? … read more
Joecamel90
Joecamel90
Technician
Associate Degree
24 satisfied customers
2011 chevy 3500 6.6 has message poor exhaust fluid quality
2011 chevy 3500 6.6 has message poor exhaust fluid quality message in center console with speed limited to 55 mph also def quality light (amber ) illuminated in cluster, were do I start? i have progra… read more
Chris (aka - Moose)
Chris (aka - Moose)
Vocational, Technical or Trade Scho
108 satisfied customers
We are having smoke out of the exhaust after idialing for
we are having white smoke out of the exhaust after idialing for awhile. … read more
Chris (aka - Moose)
Chris (aka - Moose)
Vocational, Technical or Trade Scho
108 satisfied customers
I have smoke coming from the exhaust but I had it checked,
I have white smoke coming from the exhaust but I had it checked, the injectors and the mech said they are ok within tolerances. the white smoke smells like it has water in it? but I have no loss of po… read more
David Craig
David Craig
OWNER/MECHANIC
Associates
3,927 satisfied customers
I replace the exhaust oxygen sensor, now I would like to
I replace the exhaust oxygen sensor, now I would like to reset check engine lite. … read more
Ron Z.
Ron Z.
- Chevy Tech -
Vocational, Technical or Trade Scho
2,682 satisfied customers
P0420 bank 1. 06 malibu maxx 3.5. Checked for exhaust leaks
Checked for exhaust leaks sprayed around intake looking for vaccume leakes … read more
Ron Z.
Ron Z.
- Chevy Tech -
Vocational, Technical or Trade Scho
2,682 satisfied customers
What's exhaust manifold gasket is better the steel one or an
What's exhaust manifold gasket is better the steel one or an aftermarket one that feels like rubber. I took my catalyic converter off my Chevy Malibu and it has two steel gaskets is that normal? 2005 … read more
Kevin
Kevin
workshop foreman /master tech/mot tester
0 satisfied customers
2007 2500 HD 6.6. "CLEAN EXHAUST FILTER NOW" warning came
2007 2500 HD 6.6. "CLEAN EXHAUST FILTER NOW" warning came on. Strange sounds ("chuffing" is about the closest I can come to describing it) coming from engine, temperature gauge drops to 160 position t… read more
Gabriel Grey
Gabriel Grey
Master Service Technician
Associates
175 satisfied customers
Exhaust smell with a/c on and windows closed. No it has been
we have mechanics at the factory they checked the exhaust mnaifold and a/c intake but could not pinpoint it we can take it to the dealer if needed … read more
Jerry Newton
Jerry Newton
Vocational, Technical or Trade Scho
2,066 satisfied customers
There is some exhaust fumes getting in the car, 1988 Chevy
Hi, there is some exhaust fumes getting in the car, 1988 Chevy Coup, need a mechanic to fix it… read more
eauto
eauto
self employed
High School or GED
74 satisfied customers
Cleaning exhaust fluid message then goes into engine power
Cleaning exhaust fluid message then goes into engine power reduced. Anything I can do we are in the boonies … read more
Eric
Eric
Retired
N/A
14,436 satisfied customers
Chevy 2012 - 3500 series, v-8 diesel. Exhaust fluid low
Chevy 2012 - 3500 series, v-8 diesel. Exhaust fluid low signal. Exhaust fluid fill tube will not accept additional fluid. Ran stiff wire down tube to … read more
Jerry Newton
Jerry Newton
Vocational, Technical or Trade Scho
2,066 satisfied customers
Excessive exhaust smoke and oil in the intake, approx. 500
2012 Cruze 1.4 smoking started after finding vacuum leaking from PCV valve. Have already changed the valve cover and intake manifold … read more
David Craig
David Craig
OWNER/MECHANIC
Associates
3,927 satisfied customers
I put new exhaust manifolds and split the exhaust on my 94
I put new exhaust manifolds and split the exhaust on my 94 454. The manifolds had a place for the o2 sensor so I put it there. Previously it was just behind the crossover pipe in the exhaust. Will the… read more
Eric
Eric
Retired
N/A
14,436 satisfied customers
On a 2003 Chevy 3.8 engine, can any exhaust gasses get in
On a 2003 Chevy Monte Carlo 3.8 engine, can any exhaust gasses get in the radiator other that a cracked head or bad head gasket? No oil in the coolant, it does not idle rough, no white exhaust from st… read more
David Craig
David Craig
OWNER/MECHANIC
Associates
3,927 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x