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Skyvisions
Skyvisions, ASE Certified Technician
Category: Lexus
Satisfied Customers: 14357
Experience:  Lexus Expert
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1994 Lexus while driving car check engine light comes on it

Customer Question

1994 Lexus while driving car check engine light comes on it lose power. Put obd 2 scanner on it it saids unbale to established connections. Turn car off for a minute crank it up check engine light goes off. And code code scanner says no powertrain found did it 3 times
Submitted: 1 year ago.
Category: Lexus
Expert:  Skyvisions replied 1 year ago.
What year and model do you have? Can you get it to run at all? When it says there's no communication and the key is in the on position is the yellow check engine light illuminated? How many miles are on the car? Do you have any service history leading up to this current problem?
Customer: replied 1 year ago.
1994 Lexus es300 yes it will run . after I turn car off and the check engine light goes off. 186,000. No service history they bought it a month ago. When it says no communication the yellow check engine is on
Expert:  Skyvisions replied 1 year ago.
I'm still unclear as to what's going on. The engine is running at this time and you're saying while the engine is running you're unable to establish any communication with the computer to check for codes or pull up a data list? The car idles and starts ok it just has no power for acceleration?
Customer: replied 1 year ago.
OK the car is sitting still running now no check light is on. I plugged scanner in it says no powertrain found. Now I strat driving car check engine light comes on car start slowing down losing power. While car is running and light still on I plugged up scanner it says unable to communicate.
Customer: replied 1 year ago.
I turn car off and crank back up light goes off take off car drives fine until check engine light pops on and here we go again car slows down and light comes on
Expert:  Skyvisions replied 1 year ago.
Do you know whether the intake manifold has been off of this recently or are there any signs of that? Do you live where rust and corrosion are an issue? At any time either with the check engine light on or off when the scan tool is plugged in are you able to communicate and never get any data list or codes?
Customer: replied 1 year ago.
Can't say about the maintenance on it. No I don't live were alot of rust. They only time I can get communication when check engine light is off.it says no powertrain r freeze data presently stored in computer. When check engine light comes on it read unable to established connections r communicate. I have to turn car off and restart car check light goes off and it says no powertrain r freeze data presently stored in computer
Expert:  Skyvisions replied 1 year ago.
The first thing that you need to do is check the ground on the backside of the intake manifold back by the firewall there are two ground wires held on with 2-10 mm bolts. These are the computer grounds if corrosion has gotten to these islets or the wires going to the manifold it will cause all kinds of bizarre problems with code reading and check engine light loss of power and shifting issues. Remove the bolts clean these grounds and reattach them. Make sure your ground straps from the body to the engine are also in good condition. Let me know how this goes and we continue from here. I have to step out for a couple hours I will be back on late this evening.
Expert:  Skyvisions replied 1 year ago.
Also try another scan tool just to rule out that your scan tool is not able to communicate with this vehicle. You can either rent one or bar one that would be ideal.
Customer: replied 1 year ago.
Clean grounds nothing
Expert:  Skyvisions replied 1 year ago.
Are you still unable to gain access to the engine control computer to retrieve codes? Did you try another code reader?

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