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1991 ECU location?

  #1  
Old 06-16-2015, 04:26 PM
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Default 1991 ECU location?

Can anyone help? Looking for the ECU location on a 1991 Camry, 2.2L, DX.
I looked behind the glove box and passenger kick panel and it wasn't there.
I bought a used replacement and want to change it out.

Original problem. Car died on highway.
Engine turns over but won't start.
- Timing belt good.
Got spark to plugs.
New fuel pump.
 
  #2  
Old 06-16-2015, 10:15 PM
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The ECU is under the center part of the dash. The area behind where the center console that runs between seats meets the dash.
 
  #3  
Old 06-17-2015, 04:24 PM
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Hi Joey P,

Thanks for your response. Per your note I opened up the center section of dash and did not find the ECM. I did find Denso 077300-1481 ECM Relay. I did not remove the center console, but looked there and I did not see anything (???). Still stumped.
 
  #4  
Old 06-17-2015, 09:04 PM
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This is the circuit opening relay for the fuel pump system.

The ECM should be behind this relay towards the firewall.
 
  #5  
Old 06-20-2015, 01:08 PM
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Hi Joey P.
Thanks again for your help. I did find the ECU where you said it was. I found it by pulling back the rug on the center console on the passenger side. The front of the ECU was covered by a black plastic shield making it hard to spot looking straight on. Anyhow, changed out the ECU and the car started! First time in almost a year. Drove the car home from the shop and put everything back together. Went to start the car and low and behold the car doesn't start. It turns over and no start. Sounds like no gas. I disconnected the ECU Relay (Denso box) and tried again and the car started! After trying numerous times the car (or computer) caught up and now doesn't start. Im going to try replacing the ECM Relay (Denso box) and see what happens.
 
  #6  
Old 06-20-2015, 03:22 PM
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The ECU relay is the fuel pump relay. The fuel pump will only work when the engine is cranking over or running.

Look in the engine compartment for a small plastic box, perhaps on one of the strut towers. Inside the box are electrical terminals. Use a section of wire to jump the FP and B+ terminals. This will bypass the relay and allow the pump to operate if the ign key is on.
 
  #7  
Old 06-20-2015, 06:52 PM
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I will look tomorrow and give it a shot. Thanks!
One other thing that the mechanic and I noticed. While turning the key and cranking the engine it doesn't start as mentioned, but when you let go of the key the engine briefly starts and then quickly stops. Hopefully your idea works!
 
  #8  
Old 06-22-2015, 04:53 PM
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Hi Joey P,
Found the Diagnosis plug under the hood near the driver side strut tower where you said. Per your instructions I jumped Fp and +B. Tried starting the car and no go. Same as before. I tried your method with the Denso Relay installed and removed. No difference. Any thoughts? Thanks.
 
  #9  
Old 06-23-2015, 10:28 AM
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Jumping the connections inside the box will bypass the relay and allow it to operate when the ign key is turned to ON. Make sure the fuel pump is running.

The MAF sensor has a vane switch that needs to be closed to operate the fuel pump. The switch is activated by engine intake air flow. At the MAF sensor the switch wire colors are Green (goes to fuel pump relay) and White/Black to ground. When the switch is closed, the fuel relay solenoid is grounded to activate the relay. Make sure the switch is working.

The engine has a cold start injector that operates based on coolant time. A timer turns of the injector after a short period. Determine if the injector is working at cold engine start. The relay needs to be installed for the injector to work.

Suggest if not already done so, to pickup some service info such as a Haynes manual or search the internet for files.
 
  #10  
Old 06-28-2015, 06:02 PM
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Thanks for your help Joey P. Got some updates.
Replaced the ECU Relay (new used part) same problem...no start.
Just for the heck of it shifted the car into neutral and the car started. Repeated this 10X.Started everytime.
Next day repeated the above and no start. Engine cranks but no start.
I noticed when the car does not start there is a strong smell of gas.
On the day that it did start I drove it around and the transmission is now not shifting properly. I'll probably just send it to the junk yard.Your help is much appreciated!
 

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