Chevy

Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

This answer was rated:

I have a 2003 Silverado Duramax with Allison transmission. I…

I have a 2003...

I have a 2003 Silverado Duramax with Allison transmission. I have had some trouble with it going into limp mode when pulling a trailer but now its shifting very erratically at low speeds. It surges right before shifting. I also have some electrical issues and sometimes problems starting it. It idles fine

Mechanic's Assistant: How old is the transmission? Have you noticed any leaking?

Not that I have noticed.. 200,000 miles I know it needs a transmission rebuiild but I think this erratic shifting is something electrical or fuel related

Mechanic's Assistant: Are you fixing your Silverado yourself? What have you tried so far?

I havent tried anything yes myself

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Yes that my abs light is always on and it downshifts extremely hard sometimes

Show More
Show Less
Ask Your Own Chevy Question
Answered in 1 minute by:
3/27/2018
Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 5,694
Experience: ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
Verified

Do you happen to know what the ABS trouble code is? It might be related, might not, but I'd be interested to know one way or the other.

Ask Your Own Chevy Question
Customer reply replied 4 months ago
I dont know, I just called the place that ran the codes and the guy was going to call me back. it did give a 5th gear pressure code

OK. We have had a number of problems with the pressure switch manifold in the transmission, it may all that's wrong with yours. When the TCM sees something wrong with this switch input value, it will raise line pressure all the way up and give you harsh/weird shifts.

I don't know that you need an overhaul to fix this problem, it sounds more like you might need a pressure switch manifold, which is easy to replace by removing the transmission pan. I would do more diagnostic work before getting there, but that sounds like what you are describing.

If you want to run those trouble codes by me, I am happy to look into them and give you an analysis.

Please take a moment to rate my answers by clicking on the stars at the top of the page, that's how I get compensated. Let me know if you need anything else.

Ask Your Own Chevy Question
Customer reply replied 4 months ago
what is a test I can do to verify that the pressure switch manifold is the problem?

The trouble codes will give it away, most likely. If you have a capable scan tool, you can shift through the gears and verify each switch closing and opening as it should, but the computer will definitely tell you if one of them is not working right, the TCM is watching these inputs very closely and seemingly sets a code for any hiccup out of this manifold.

Ask Your Own Chevy Question
Customer reply replied 4 months ago
you are saying in need to get a scan tool and do what exactly? just to make sure we are on the same page, the main issue im having is that its shifting erratically especially at low speeds . Its impossibly to drive it smoothly.. The code it gave was a P07xx transmission code

I would need the rest of that P07XX code to point you in the right direction, but you mentioned that it was related to a pressure switch.

When looking at data on the scan tool, you can simply drive it while watching (or recording for later playback, to do this safely) the pressure switch activity. There is a data line for each switch, and the TCM will simply tell you what the switches are doing. If the TCM commands 5th gear and the pressure switches do not respond the way it expects, you get a code and you get default line pressure and possibly limp mode, and you can record this/watch this as it happens and pick apart the data to see exactly what is going on.

Let's start with a trouble code, though, to make sure we are going in the right direction.

Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 5,694
Experience: ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
Verified
Jerry Newton and 87 other Chevy Specialists are ready to help you
Ask your own question now
Customer reply replied 4 months ago
U1000 - class to data link malfunction
P0522 - Oil pressure sensor
C0040 - right front wheel speed sensor circuit/ABS

U1000 is a very generic code that indicates a communication problem. It's probably stored in history, not current, and diagnosis of it is impossible unless the symptom/code is current. It is not unusual to find U1000 codes in just about any GM car or truck, any hiccup will cause this code to set, and it usually isn't related to anything the vehicle is doing, and is not a symptom by itself. It won't turn on a warning light or anything, if you never checked codes with a scan tool, you'd likely never know that there's a U1000 banging around in one of the computers.

P0522 is pretty straight forward, the ECM sees low voltage (or has seen low voltage at some point) at the oil pressure sensor. I would just put a new sensor in to correct this.

C0040, as you describe, indicates a problem with the RF ABS wheel speed sensor. Not related to any transmission or shifting concern.

Where is the P07XX code you mentioned earlier?

Ask Your Own Chevy Question
Customer reply replied 4 months ago
I ran the codes a second time and that particular area did not come back up. I don't remember the exact code but I know it said that it was the load line pressure in the fifth gear and that is why it triggered it. Yesterday I messed with the wiring harness is in the TCM to make sure nothing was broken, I unplug the batteries for a little while and plug them back in. I also found that the electrical connection for a map sensor that was on top of the turbo I had broken and I fastened it back together. When I got into drive it it worked really well for an hour or so and then started doing all the same symptoms again. The symptoms slightly worse and until they were back to the exact level as before. I don't know if this helps but it is definitely what happened

When you disconnected the batteries, it sounds like it reset the adapts, which is the learning portion of the TCM. It goes back to a default, then over time it learns the shifts again, watching the shift time in milliseconds and making small adjustments to the line pressure. It sounds like it's relearning, but it's also going back to its old habits.

If there are no transmission codes, I wouldn't replace any parts on it yet. Let the computer figure this out, if it's acting weird enough, it will eventually give you a trouble code that you can use to sort out what's causing the issue. It might be a worn out transmission, but it could also be a bad switch manifold, a bad PRNDL switch, a bad shift solenoid.... it can get expensive just throwing parts at it. Wait until you get the trouble code again, and address it specifically from that perspective.

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 Jerry Newton Your Own Question
Jerry Newton
Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 5,694
5,694 Satisfied Customers
Experience: ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.

Jerry Newton 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
Im looking to find a good truck to pull a race trailer 24
im looking to find a good truck to pull a race trailer 24 ft. … read more
Jared D
Jared D
Shop Supervisor
Bachelor\u0027s
3 satisfied customers
I have a 2004 Chevy Silverado Duramax with a 5 speed allison
I have a 2004 Chevy Silverado Duramax with a 5 speed allison transmission. last Year I needed to replace the nsbu switch, and everything worked fine until approx 2 weeks ago. I thought the switch was … read more
BOBBYSS
BOBBYSS
TECHNICIAN/ADVISOR
Associate Degree
8,343 satisfied customers
Driving down the highway, or even sitting at a red light,
driving down the highway, or even sitting at a red light, the transmission will ocassionally throw a code, and then it goes into limp mode … read more
Nate
Nate
Automotive Technician
Automotive Trade School Degree
84 satisfied customers
Chevrolet Silverado 2500HD: have a 2004 silverado 2500 with
have a 2004 silverado 2500 with duramax and allison put in 4wd the other night to pull on a truck a little no real strain just holding pressure now it is throwing coeds pops out of gear and says "rang… read more
BOBBYSS
BOBBYSS
TECHNICIAN/ADVISOR
Associate Degree
8,343 satisfied customers
chevy 2500hd: after hauling a trailer about 300 miles in my
after hauling a trailer about 300 miles in my 2003 duramax 2500hd allison trans. it started giving me problems I checked codes they where over heat & 5th. gear out of ratio.the trans. shop said it had… read more
BOBBYSS
BOBBYSS
TECHNICIAN/ADVISOR
Associate Degree
8,343 satisfied customers
Chevrolet Silverado 2500 HD Classic LT: 06 silverado 2500 duramax/alli
06 silverado 2500 duramax/allison Transmission is downshifting to passing gear very hard. also seems to shift up through fourth rather quickly on normal acceleration. It tends to want to stay in fourt… read more
Chris (aka - Moose)
Chris (aka - Moose)
Vocational, Technical or Trade Scho
108 satisfied customers
GM 3500 Silverado: Does the Allison transmission in my 2003
Does the Allison transmission in my 2003 Silverado 3500 have a computer? If so, can the program be altered? I'm pulling a 6 1/2 ton 5th wheel and the transmission down shifts in tow mode on downhill g… read more
Anthony
Anthony
Master Automobile Technician
Vocational, Technical or Trade Scho
8,789 satisfied customers
Shevy Silvarado: I have a 2009 Silverado 2500 HD 4WD LTZ with
I have a 2009 Silverado 2500 HD 4WD LTZ with Duramax engine and Allison transmission. It is equiped with the integrated trailer brake control. I occasionally pull a 5th wheel trailer with electric bra… read more
Til Forrer
Til Forrer
gm auto technician
Vocational, Technical or Trade Scho
75 satisfied customers
2002 chevy: allison..the engine , ABS and park brake lights are
i have a 2002 chev silverado ext cab longbox 6.6 duramax and allison 1000 . the engine , ABS and park brake lights are on and will not shift. have read the codes and all that comes up is a transmissio… read more
BOBBYSS
BOBBYSS
TECHNICIAN/ADVISOR
Associate Degree
8,343 satisfied customers
2001 Chevy: Duramax..serviced..Towing..8600lb trailer for 8 hours
2001 Chevy K2500 Duramax with Allison transmission, 120K miles, engine/tranmission just serviced 2 weeks ago. Towing 8600lb trailer for 8 hours today at 70mph no problem. Temperatures and pressures al… read more
Mr GOODWRENCH
Mr GOODWRENCH
Technician
Associate Degree
145 satisfied customers
2003 duramax silverado allison 96..shifting..plug into a scanner
I have a 2003 Duramax Silverado Allison 96,000 miles.Transmission is not shifting right I had it plug into a scanner and got codes U2104, U2106, U1152, U1041, U1024. What do these codes mean? I just s… read more
Hal
Hal
owner/service tech
Vocational, Technical or Trade Scho
848 satisfied customers
2004 2500hd duramax lly keeps going into limp mode seems like
2004 2500hd duramax lly keeps going into limp mode seems like after warms up almost every time. we have replaced injectors at 50,000 miles and computer at the same time and about a month ago injector … read more
Allisonforeman
Allisonforeman
Allison transmission foreman
High School or GED
300 satisfied customers
driving at about 65 mph my tranny sliped...only work in 3rd gear.
I was driving at about 65 mph my tranny sliped. On the dash it said shift range inhibited. It will only work in 3rd gear. I have a 2003 silverado duramax allison transmition . What do you think happen… read more
XSTREAMAUTO
XSTREAMAUTO
auto tech
High School or GED
40 satisfied customers
I have a 2007 Chevy Silverado 3500 Dually and the tow haul
I have a 2007 Chevy Silverado 3500 Dually and the tow haul mode is not working properly. The button works fine and in fact I've had the shift column replaced. It seems like it's stuck in tow haul mode… read more
michael
michael
High School or GED
582 satisfied customers
2001 Chevy: neutral indicator switch..606 duramax..out of Limp Mode
I replaced the neutral indicator switch on my 2001 Chevy 3500LT, 606 Duramax with Allison transmission - how do I get it out of Limp Mode? Stays in 3rd gear… read more
Steve
Steve
Vocational, Technical or Trade Scho
204 satisfied customers
gear shift..wont shift..garage it runs fine till it gets real cold
i have a 2003 silverado,duramax diesel,4 wheel,5 speed allison trans.when it gets real cold and you put it in gear it says gear shift inhibited on the computer.it wont shift in the proper gears.If i w… read more
goodwrench9124
goodwrench9124
Lead Tech/ Shop Leader
Vocational, Technical or Trade Scho
2,571 satisfied customers
2007 chevy: i was driving the check engine light came..bumper..trailer
i have a 2007 chevy duramax with the allison transmission. while i was driving the check engine light came on and the shift pattern of my truck became really different, even though i was pulling an em… read more
Mcgruder73
Mcgruder73
Auto Technician
Associate Degree
I have a 2003 Chevy Silverado P/U with a Duramax Diesel and ...
I have a 2003 Chevy Silverado P/U with a Duramax Diesel and Allison Transmission. Yesterday while driving at Highway speeds, it downshifted and then it was completely out of gear. I had a message that… read more
Expert
Expert
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