CEL 55, No. 2 Knock Sensor Malf. (1994) (1 Viewer)

Joined
Aug 22, 2003
Messages
401
I'm having a reacurring check engine light. It's a CEL code 55, which is the No. 2 knock sensor. Open or short in No. 2 knock sensor circuit, No. 2 knock sensor bad or loose.

I've got the FSM, but can't find the section on how to test this sensor, or anything on replacing it. I want to test to see if there could be a short somewhere or if I need to replace it. Can you tell me what pages in the 94 manual deals with this?

I called Toyota of Dallas, all they could tell me is they would be happy to check it out for me $88 to tell me what is wrong with it. He couldh't tell me how much to fix it. I'm on a tight budget, and like to fix it myself if at all possible.

Anybody????


Thanks in Advance.

Bryan
 
Joined
Aug 22, 2003
Messages
401
I found the pages in the FSM (EG304) that deal with the knock sensor.

If you have ever changed one, or had problems with this, I still would like any information you care to share or send me a PM.

Thanks,
Bryan
 
Joined
Aug 4, 2004
Messages
926
Location
Spokane WA, USA
I can't tell you how to check the sensor, but I can offer some advice on what to look for.

I broke the plastic wire connector socket clean off one of the knock sensors on my '96 when replacing the head gasket - I wacked it with a wrench I think - anyway - the entire top portion broke off, leaving the two metal pins intact.

I removed the sensor and reattached the plastic part using epoxy and reinstalled it after letting it cure overnight. It is still working fine after 20K miles.

If your sensor has mechanical damage that is causing an open circuit, it may be repairable. Give it a try before forking out big $$.

John Davies
Spokane WA
 
Joined
Aug 22, 2003
Messages
401
Thanks John for the tip. I also got a tip from Cruiser Dan, about swaping them front to rear, and see if the CEL light code changes, to front sensor malf. instead of rear sensor malf like it has now. All this happened after my PHH blew, and maybe some water messed up the wire or conections. I'll dig into it this weekend if it doesn't rain.
 
Joined
Aug 22, 2003
Messages
401
I finally fixed this problem, and since it's the only knock sensor problem that I found by my searches, I thought I would post the update. This problem showed up after my PHH blew, the week of Christmas. I thought this might have had something to do with it, and maybe it did. For one thing, I was looking in the wrong place for it. I was looking in my FSM and it looked like it was up high, right under the intake manifold, but it is actually just to the left of the PHH and at about 10:00 Oclock angle and maybe 5" away. The problem turned out to be the plastic connection had completely broken away from the rest of the part.
It looked beyond glueing it back together which worked for John, so I broke down and bought a new part from Chris King at Toy of Dallas. Chris runs the Toyota Trail Riders club and has a cool black Tacoma.
Replacing it was a pain, and I'm glad to be done with it. I bought a 6 point 1 1/16" deep socket since I couldn't find a 27 mm deep 6 point one. It actually measures 1.061 across the flats on the old one so either one should work perfectly fine. You will want a 6 point and a deep socket works better. I used a 1/2 drive 1 1/16" deep 6 point, with a 1/2 x 3" extension, then a 3/8 x 1/2 adapter, then a 3/8 x 3" extension and a offset Craftsman wratchet with a swivel head. Getting the old one out was fairly easy once I got the socket/extensions figured out. I didn't even remove the tire or jack it up but it would have been easier to do so. My biggest problem was removing the broken plastic male socket from the female plug socket and wire. It actually took longer to do get this old piece out of the socket than taking the old sensor out and putting in a new one. Once I got the bad plug from the good socket, it was easy to just snap the female plug onto the new male plastic plug end on the new part. I drove it around for a while tonight and no more CEL. HURRAY!!!! This CEL would come on about a mile from my house, when the engine came up to full normal temp. and you could feel it cut the power. Felt like I was loosing half my power with this. I only drove it once in a while and just a few miles but it's been a pain in the asphalt, for sure. I kept trying to get the old one to work, but I should have just replaced it right off the bat. I have pictures to post of this part when I figure out how to post them. Thanks for the help from all I've talked to about this.

Bryan
 
Joined
Oct 24, 2004
Messages
459
Location
Lafayette, Louisiana
P0325 solved here as well....thanx!

I finally fixed this problem, and since it's the only knock sensor problem that I found by my searches, I thought I would post the update. This problem showed up after my PHH blew, the week of Christmas. I thought this might have had something to do with it, and maybe it did. For one thing, I was looking in the wrong place for it. I was looking in my FSM and it looked like it was up high, right under the intake manifold, but it is actually just to the left of the PHH and at about 10:00 Oclock angle and maybe 5" away. The problem turned out to be the plastic connection had completely broken away from the rest of the part.
It looked beyond glueing it back together which worked for John, so I broke down and bought a new part from Chris King at Toy of Dallas. Chris runs the Toyota Trail Riders club and has a cool black Tacoma.
Replacing it was a pain, and I'm glad to be done with it. I bought a 6 point 1 1/16" deep socket since I couldn't find a 27 mm deep 6 point one. It actually measures 1.061 across the flats on the old one so either one should work perfectly fine. You will want a 6 point and a deep socket works better. I used a 1/2 drive 1 1/16" deep 6 point, with a 1/2 x 3" extension, then a 3/8 x 1/2 adapter, then a 3/8 x 3" extension and a offset Craftsman wratchet with a swivel head. Getting the old one out was fairly easy once I got the socket/extensions figured out. I didn't even remove the tire or jack it up but it would have been easier to do so. My biggest problem was removing the broken plastic male socket from the female plug socket and wire. It actually took longer to do get this old piece out of the socket than taking the old sensor out and putting in a new one. Once I got the bad plug from the good socket, it was easy to just snap the female plug onto the new male plastic plug end on the new part. I drove it around for a while tonight and no more CEL. HURRAY!!!! This CEL would come on about a mile from my house, when the engine came up to full normal temp. and you could feel it cut the power. Felt like I was loosing half my power with this. I only drove it once in a while and just a few miles but it's been a pain in the asphalt, for sure. I kept trying to get the old one to work, but I should have just replaced it right off the bat. I have pictures to post of this part when I figure out how to post them. Thanks for the help from all I've talked to about this.

Bryan

Byan, after searchinng and searching the forums for the same issue....the Hayne Service Manual said the knock sensor was UNDER the manifold and that the intake and plenum must be removed to access...WRONG. It was a broke wire (due to MY HANDS feeling around to see if I could double-check the PHH (went with the high temp blue silicone here from http://1fzfephh.com/ but had another shop install it. What happened in my case was that the wire broke off of the plastic connector...which cracked while pulling on it...It was dark, but I was able to feel that the metal end was still on the wire and I was able to slip it firmly over the sensor's plug-end. I plan to remove, place heat/shrink wrap and replace.

Thanx owed to your post for the repair/solution.
I too search all over for info...the thing is, the knock sensor must
be well made and likely not to fail for a long time.
That's probably why not much info to be found on it.
 
Joined
Jul 7, 2005
Messages
236
Location
MA
What happened in my case was that the wire broke off of the plastic connector...which cracked while pulling on it...It was dark, but I was able to feel that the metal end was still on the wire and I was able to slip it firmly over the sensor's plug-end. I plan to remove, place heat/shrink wrap and replace.


I never updated my thread on this, but my wire broke off the
#1 knock sensor with out enough room to solder it back.
Cdan sold me the pigtail that connects to the wiring harness
on on end and a new knock sensor connector on the other end.

I ended up cutting the harness end off as I couldn't find it's
connector mate and just soldered the new connector on with
some heat shrink tubing as well.
 

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