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sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 22807
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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When I get up to 20mph it won't go any faster. It's a 2007

Customer Question

When I get up to 20mph it won't go any faster. It's a 2007 grand Cherokee with 112000 miles did get trans replaced 6 months ago and it was used with 44000 miles on it. I replaced the battery just last week because it had a dead cell and was cause some intermittent acceleration once I got it replaced it drove fine until a few days ago it won't go past 20 any prognosis anyone can come up with
JA: Did you test the battery with a voltmeter? And have you ever changed one before?
Customer: The new battery I didn't see a need to test it I've had it for a week and a half
JA: Are you fixing your Grand Cherokee yourself? What have you tried so far?
Customer: No I'm not fixing it myself I wish I could but I went and had the check engine light tested but everyone seemed to think the gears are warn with the code it gave but I wish i knew something to try now the other day I had let it run for 10 minutes after it 1st did that and it started running fine
JA: Anything else you want the mechanic to know before I connect you?
Customer: That's all I have goin on at this time
Submitted: 9 months ago.
Category: Jeep
Expert:  sprinkles08 replied 9 months ago.

Hello and welcome to JustAnswer!

I suspect that the reason it won't go any faster is because the trans is in limp in, but it could be an engine power related issue.

The first step in diagnosing the problem will be to use a scan tool or code reader to see what fault codes are setting in the engine and trans controllers and then testing can be done from there. Do you know what codes are setting?

Customer: replied 9 months ago.
Po868 is the only thing showing when I got it scanned today
Expert:  sprinkles08 replied 9 months ago.

Which engine do you have?

Customer: replied 9 months ago.
4.7
Expert:  sprinkles08 replied 9 months ago.

Has the fluid level and condition been checked?

Customer: replied 9 months ago.
No I haven't had anything checked
Expert:  sprinkles08 replied 9 months ago.

This code is for low line pressure and could be a sensor issue but if you're having symptoms from the trans then there may be an actual line pressure issue and the trans is slipping. The first thing that should be done is check the fluid level and condition. If the fluid is burnt that indicates clutch slippage.

Customer: replied 9 months ago.
Oh wow so with what ur saying it would possibly need some work done on the trans or even have to be replaced
Expert:  sprinkles08 replied 9 months ago.

Yes, that's possible. If it has been driven with the line pressure actually low then clutch damage is very possible.

Customer: replied 9 months ago.
Oh ok then that's always great to hear well I do thank you for at least where to start with this situation and go from there
Expert:  sprinkles08 replied 9 months ago.

You're welcome and good luck with it!