Code 52 Revisited...
04-09-2010, 01:41 PM
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Code 52 Revisited...
Hello
New member here, but long time mechanic. I do however have limited Toyota (and automobile) experience. I work mainly Cummins ISB, ISC, Cat C7, and Detroit S50's. Anyway, just bought a '89 'yota pick-up to tear up out in the desert. It's a single owner 4x4 m/t, Cal spec 22RE Deluxe. Truck has 210k, 5k on long block.
When I got the truck, it ran terrible. Replaced the injectors with reman (cleaned) injectors. What a difference. Also my code 25 went away! Then the engine would surge terribly above mid-throttle. Checked the VAF sensor and found that the ohms went haywire after partly opening the flap. Replaced the VAF sensor with an aftermarket reman, and that seems to have resolved that issue. Only thing left is the infamous code 52.
I checked the on-line FSM, and it is lacking in good info on the knock sensor. I looked at the diagram for the ecm, and checked continuity between the knock sensor connector and what the fsm shows as the correct ecm pin for the m/t. no continuity. Checked all other pins and found continuity with the pin marked "Te2" (KNK pin on the a/t diagram). Now I have to wonder if the diagram is correct. Logically if I had a mismatched harness/ECM, the truck shouldn't run. I replaced the connector and pigtail at the sensor, checked ground between block and B-, and cleaned the sensor threads as well as the block threads. Still have the code. Also, the truck runs good, except on take-off, I get a series of backfire pops, and the launch is very slow. Checked timing per fsm and it is correct. Before I throw a ($$$) sensor at it, is there a way to check the sensor. The code discreption says no signal for 25 rev above 2K rpm. With no knocking, what signal is the ECM looking for? Ohms? Ground? Voltage? Help out an old diesel mech here and help me to understand this system.
Thanks...
John
New member here, but long time mechanic. I do however have limited Toyota (and automobile) experience. I work mainly Cummins ISB, ISC, Cat C7, and Detroit S50's. Anyway, just bought a '89 'yota pick-up to tear up out in the desert. It's a single owner 4x4 m/t, Cal spec 22RE Deluxe. Truck has 210k, 5k on long block.
When I got the truck, it ran terrible. Replaced the injectors with reman (cleaned) injectors. What a difference. Also my code 25 went away! Then the engine would surge terribly above mid-throttle. Checked the VAF sensor and found that the ohms went haywire after partly opening the flap. Replaced the VAF sensor with an aftermarket reman, and that seems to have resolved that issue. Only thing left is the infamous code 52.
I checked the on-line FSM, and it is lacking in good info on the knock sensor. I looked at the diagram for the ecm, and checked continuity between the knock sensor connector and what the fsm shows as the correct ecm pin for the m/t. no continuity. Checked all other pins and found continuity with the pin marked "Te2" (KNK pin on the a/t diagram). Now I have to wonder if the diagram is correct. Logically if I had a mismatched harness/ECM, the truck shouldn't run. I replaced the connector and pigtail at the sensor, checked ground between block and B-, and cleaned the sensor threads as well as the block threads. Still have the code. Also, the truck runs good, except on take-off, I get a series of backfire pops, and the launch is very slow. Checked timing per fsm and it is correct. Before I throw a ($$$) sensor at it, is there a way to check the sensor. The code discreption says no signal for 25 rev above 2K rpm. With no knocking, what signal is the ECM looking for? Ohms? Ground? Voltage? Help out an old diesel mech here and help me to understand this system.
Thanks...
John
04-23-2010, 10:37 AM
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Thanks for all the informative replies! 
Went ahead and replaced the sensor. Found one on Amazon.com for $135. so I took the chance. Problem solved.
John
Went ahead and replaced the sensor. Found one on Amazon.com for $135. so I took the chance. Problem solved.
John
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