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2001 Lexus RX300

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4 years 2 months ago #36576 by Kupe2222
2001 Lexus RX300 was created by Kupe2222
The engine turns over but no start. The security light is on. It's my car and my keys so it should not be on. No obd communication. After watching some of scannerdanner's videos on Youtube, I thought it may be a 5 volt reference problem with a short in one of the sensors because one of the videos he did had my same issues (turn over, no start, no obd communication with the computer). I just don't know much about electrical in cars so if someone could give me some advice on where to start, I would really appreciate it. I tried to start by testing my MAF sensor because it was easy to get to. It has five wires. 3 wires are putting out about 12 volts, one at 8 volts and one at 0.5 volts. Any help would be appreciated. I have already had this at a shop and the dealer and I'm $800 in the hole with no progress. Thanks!

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4 years 2 months ago #36577 by VegasJAK
Replied by VegasJAK on topic 2001 Lexus RX300
Your MAF is a MAF and IAT combined. Three wires are for the MAF and two for the IAT (intake air temp sensor). I think you're testing incorrectly. Using a DVOM in DC voltage, black lead to battery negative. Red lead, back probe each wire.

I do not have a wiring diagram for your car, but the three wires for the MAF when probed should show 12v power, 5v signal, .1mv or less for ground. This is sensor plugged in with KOEO.

"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
The following user(s) said Thank You: Noah

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4 years 2 months ago #36601 by Kupe2222
Replied by Kupe2222 on topic 2001 Lexus RX300
I think this is the right wiring diagram. Thanks for the help. I think I was testing the wires incorrectly.
Attachments:

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4 years 2 months ago #36604 by VegasJAK
Replied by VegasJAK on topic 2001 Lexus RX300
b/r - 12v
g/b - ground (for MAF)
y/r - MAF signal
l/b - IAT sensor
br - ground

"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does

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