Chevy

Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

Pcm fuse blows immediately. Can't even plug in all the way.

Customer Question
Pcm b fuse blows...

Pcm b fuse blows immediately. Can't even plug in all the way. No dash lights on speedo cluster. Won't communicate with scanner. 03 duramax lb7

Mechanic's Assistant: Sometimes things that you think will be really complicated end up being easy to fix with a Chevy. The Chevy Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best. Are you hoping to fix this yourself?

Batteries died. Charged both up, about 2 months old. Had dash lights but no glow plug light. Now no lights on cluster. Starter has not even clicked. Started up and idled for 15 minutes about a month ago to recharge batteries with no issues. Have tried disconnecting batteries for 1/2 hour to reset computer, no power to ecm fuse and pcm b keeps blowing.

Submitted: 2 years ago.Category: Chevy
Show More
Show Less
Ask Your Own Chevy Question
Answered in 4 minutes by:
3/2/2016
Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 33,361
Experience: 14 years GM dealer Technician.
Verified

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Is anything after market wired into the vehicle at all right before this issue occurred or to try and correct this issue?

Let me know so we can continue,thanks Pete.

Ask Your Own Chevy Question
Customer reply replied 2 years ago
No. Stock except trailer brake installed in 03.
Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago

O.k.,The PCM B fuse energizes the EDU relay and when this relay is energized it powers the ECMRPV and EDU fuses.So these fuses will not have power until the PCM B fuse fault is corrected.

For some odd reason the diagram is trying to tell me the PCM B fuse powers the fuel pump relay for a diesel engine and your model shouldnt use this relay.Double check in your under hood fuse panel to see if this relay is installed and if it is remove it and see if the fuse still shorts out and let me know.

The PCM B feeds the ECM (engine control module) as well here.If the engine control module has an internal electrical short in it this will occur and the ecm would need replaced.If there is a short in the wiring leading from the PCM B fuse to the engine control module this will occur as well and the wiring would need traced and inspected and repaired.If there is a short in the wiring leading from the PCM B fuse to the EDU relay this will also occur and the wiring would need repaired.

With this fuse being blown this will cause all of the issues you see here.You will need to locate the short by removing the edu relay to see if the relay is the cause needing replaced,removing the fuel pump relay (if equipped) to see if this relay is the cause needing replaced,or checking the wiring inside the fuse box running from the pcm b fuse to the edu and fuel pump relay for any shorts needing repaired,check the wiring from the pcm b fuse to the ecm to see if any wiring is at fault needing repaired.If all of these are o.k.and the short still continues then the ecm needs replaced.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Ask Your Own Chevy Question
Customer reply replied 2 years ago
Removed F/PMP fuse, and still blows fuse. Was that the right one?
Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago

It would be labled Fpump relay or fuel pump relay and is square and large in shape,its not a fuse but a relay instead.I dont think your model has this although my diagram says your diesel does I havent seen one in a diesel myself.

Ask Your Own Chevy Question
Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago

I suspect the short is in the edu relay or wiring to the ecm or the ecm itself needing replaced.This will have to be checked/tested further to pinpoint and repair the fault here.

Let me know if you need anything else and feel free to rate my help here.

Thanks Pete

Ask Your Own Chevy Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a chevy mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Pete Your Own Question
Pete
Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 33,361
33,361 Satisfied Customers
Experience: 14 years GM dealer Technician.

Pete 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

15,756 satisfied customers

GM Grand Master Technician 2007. 14 years experience.

Gary

Gary

Chevy Technician

9,642 satisfied customers

15 years GM master tech

Tim&#039;s Auto Repair

Tim's Auto Repair

mechanic

8,884 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

2,953 satisfied customers

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

Ron Z.

Ron Z.

- Chevy Tech -

2,836 satisfied customers

18+yrs experience. State Inspector and Chevy Diagnostics

< Previous | Next >

Related Chevy Questions
I have a 87 Chevy pick up 1/2 ton short bed. it start and
ok I have a 87 Chevy pick up 1/2 ton short bed. it start and run .but when i drive it for 1000 feet or more sometimes it blows the 10 amp to the ECMB put new in and same thing check gr,and it stop for… read more
heavy_chevy_396
heavy_chevy_396
Vocational, Technical or Trade Scho
2,518 satisfied customers
03 avalanche -cranks no start- have fuel pressure at rail,
03 avalanche -cranks no start- have fuel pressure at rail , pump engages. Checked fuses, replaced fuel pump 3 months ago, new crank sensor last night, scanned no codes last night and today, reset pass… read more
Ivan Alvarez
Ivan Alvarez
Lead technician
192 satisfied customers
2004 Duramax LB7 will not start. I replaced the fuel
2004 Duramax LB7 will not start. I replaced the fuel injectors and glow plugs on the drivers side. After completing, I started the truck and everything worked as expected. I turned the truck off and p… read more
Dan
Dan
Auto Mechanics 1&2/diesel mech
I have a 2005 silverado duramax 4x4 Speedo not working Had
I have a 2005 silverado duramax 4x4 Speedo not working Had cluster just redone Changed speed sensor What else?… read more
Kavey
Kavey
86 satisfied customers
Im gettign DTC P0236, 0380, 0381, 0540, and 1621 on cold days.
I'm gettign DTC P0236, 0380, 0381, 0540, and 1621 on cold days. Any ideas what it is? The mech told me to get a new PCM for starters. I have a bully dog triple, on my 03 Duramax 2500… read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
A scanner shows speedreplaced guage cluster with used still..speedo
2000 1500 pick up 4x4 speedometer does not work hooked to a scanner shows speed replaced guage cluster with used still no work every thing else on cluster works just no speedo… read more
GM Tech (Cam)
GM Tech (Cam)
Chevy Technician
Vocational, Technical or Trade Scho
15,756 satisfied customers
1998 S 10 pu, 2.2L, 5 spd manual trans.truck..re-start..psi..fuel pump
1998 S 10 PU, 2.2L, 5 spd manual trans. truck died while driving, would not re-start, towed home. checked fuel PSI, none, fuel pump does not run. checked fuel pump relay with 9vlt battery, relay is op… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,642 satisfied customers
2001 chevy: durmax truck runs good..injectors..heater relay
2001 chevy 6.6 durmax truck runs good for 15 to 20 minuts than losses power if you shut it down and re start it is ok for a while than losses power also a code for large fuel leak but no visable leak … read more
John
John
Master A.S.E Automotive technician
2 YEARS COLLEGE
4,071 satisfied customers
c2500: duramax & allison auto matic..tire..fuses..hood
2005. c5500 duramax & allison auto matic, our tire service truck , shut it off on a job went back to start , cranks over just fine will not fire up.plenty fuel the primer gets hard quickly , used our … read more
John
John
Master A.S.E Automotive technician
2 YEARS COLLEGE
4,071 satisfied customers
2006 Chevy: 6.6l duramax diesel Engine starts and stalls..turn key
2006 Chevy Express with 6.6l duramax diesel Engine starts and stalls within 5 seconds turn key off, restart, does the same thing again runs smooth for those 5 seconds and stalls… read more
GM Tech (Cam)
GM Tech (Cam)
Chevy Technician
Vocational, Technical or Trade Scho
15,756 satisfied customers
Batteries went bad, took them out to buy new ones, put new ones..Crank
I have a 2003, 2500 hd duramax. Batteries went bad, took them out to buy new ones, put new ones in 2 doys latter, would not start. Crank but not start. Take the pcm-b fuse out and reinstall it, then i… read more
Mcgruder73
Mcgruder73
Auto Technician
Associate Degree
97 lumina: that the speedo wasnt working..95 not 97, obd1 not obd2
Abut a month ago, I asked you some questions about a 97 lumina 3.1 that the speedo wasn't working. Well, I found out it is a 95 not 97, OBD1 not OBD2. Are the test procedures the same? I took a 25 dol… read more
Randall
Randall
Auto Technician / Consultant
Vocational, Technical or Trade Scho
69 satisfied customers
Chevy: kit..allison..1st gear triies to lock rear wheels up
I have just put a bullydog shift aggressor kit in my 03 chevy duramax/allison will not shift out of 1st gear triies to lock rear wheels up. I keep every thing clean when I put it together. code p0700,… read more
Dave Nova
Dave Nova
Chevrolet Technician
Associate Degree
7,092 satisfied customers
03 chevy: The check engine light came on..OBD II..glow plug
I recently purchased an '03 chevy silverado with the 6.6 duramax. The check engine light came on. A friend used his OBD II reader and showed code P 0380 glow plug heater circuit "A". The service recor… read more
John
John
Master A.S.E Automotive technician
2 YEARS COLLEGE
4,071 satisfied customers
We have a 2004 Chevrolet W5500 and need to find the fuse ...
We have a 2004 Chevrolet W5500 and need to find the fuse that controls the automatic shifting of the transmission.… read more
Bob
Bob
Vocational, Technical or Trade Scho
2,784 satisfied customers
2003 Chevy: trouble codes p0380 and p1621 how do I fix it
I have a 2003 Chevy Duramax and am getting trouble codes p0380 and p1621 how do I fix it? It will not start.… read more
Mazda Ed
Mazda Ed
Lead Technician
High School or GED
1,963 satisfied customers
1997 GMC: the glow plug lite..crank..fuel pressure..fuel pump relay
I need help with a 1997 GMC 3500 HD 6.5 L Diesel I turn ign. on and the glow plug lite sometimes wont come on and if it dosn,t come on engine will crank but wont start and sometimes if you try again i… read more
Mazda Ed
Mazda Ed
Lead Technician
High School or GED
1,963 satisfied customers
Chevy: wont start..computer says po380 Glow Plug/Heater ckt problem.
I have a Chevy Duramax that won't start. The computer says PO380 Glow Plug/Heater CKT problem. What does that mean. The truck will only start with starting fluid. I have replaced the glow plug relay a… read more
frank
frank
Vocational, Technical or Trade Scho
1,892 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