'94 Code Reader

Anyone know where / how I can get this engine code read? I don't know if there's a trick for counting lights after startup, etc...

Thanks! It looks like it's a code 52 - knock sensor... does anyone know if this code means the sensor is not sending signal, or that it's sending a knock signal?

I don't get the light at immediate startup... it has to run for a few (after idle slows down).

I've found some information that suggests that code 52 is knock sensor - bad signal (faulty ks)... 53 is a bad computer... and if it's just detecting knock, it won't throw a code at all...

so, is there anyway to make the sensor inactive - so it doesn't throw a code? Car runs great... until the darn ks starts to retard the timing... when we did the head gaskets, we noticed that the sensor was a little brittle, but it was nearly $200 for a replacement... we were hoping it would be ok...

Most likely is that the cable or connector to the sensor was damaged when you installed the head gasket on that engine or the connection is corroded and needs to be cleaned.

http://www.automotiveforums.com/vbulletin/showthread.php?t=313671

http://www.asashop.org/autoinc/JULY/techtips.htm

You can test the sensor by continuity between the connecting pin and the sensor body. There should be no continuity. Knock sensors appear to be hard to kill though...

I considered replacing the cable when I had it all apart, but when I called local dealership they told me the cable was part of the entire wiring harness...

Is the recommendation to go to lowe's and grab some copper? : ) Or were they just plan wrong... (I'm guessing/hoping the latter). Anyone know a site online where I can pick up the cable cheap?


Also, I didnn't see where it said in these 2 links... obviously, it will scream if it gets no signal... I'm wondering if it throws a light also when it detects knock? I'm just wondering if it's retardig the timing because it's not getting a signal... or if it's really not affecting the engine, just not doing it's job of being a protector...

It might really be that cable... I drove it for 5 minutes, no light... then stopped at a traffic light and got the light... the timing isn't perfect yet, but the light was absolutely useless (way off) we just lined it up TDC and did a visual, then adjusted by ear.

"...when I called local dealership they told me the cable was part of the entire wiring harness..."

That may be the way they sell it.

In the first link I posted, all that was needed was cleaning of the connection for that cable.

If the connection is bad or the sensor shorts out, the ECM defaults to retarded timing and sends an error.

There is no error code when the sensor detects pinging. It simply signals the ECM that there is pinging and the ECM retards the timing until no more signal.

perfect - ty so much, that's exactly what I needed to know : ) I can't get the car to go over 4000 rpm, making it impossible to get to 70mph on the freeway... so, I was sure it's either retarding the timing, or just not advancing it. Sounds like a error code 52 would definitely retard it...

looks like I'll be taking that intake off again : ( Oh well... wish I had known about checking it via continuity before... so, no continuity = good sensor, work on wire...

If there is continuity, is it because the little mic thing inside is touching the insides somehow? : )

Before you do serious work, clean the contacts on the connector mentioned in my link above.

it sounds like it was a connector by the air box... I'll try to figure out which one, before I take anything apart...

The knock sensor did not look that great when I was in there... but it seemed worth trying it, since it was $170 + tax... of course, now I may end up spending 2 days taking the whole thing apart again : ) At least now I know how to test the sensor it's self... and I think I can check the wire via continuity also.

Anyone have any recommendations for online parts, just in case I need them? If I end up going down to the sensor, I would like to at least replace the wire (if it's cheap).

back to the drawing board... it died on me on a test run... 2 miles from home, couldn't get it running again... leaves me with 1 more AAA tow until the end of Feb. : (

Not sure what's up with it... just finishing a clutch in the garage, so it'll be tomorrow evening before I can get at it again...

Timing belt?

hope not - put a brand new one on when we did the head(s)... and the tensioner was insanely tight (compressing it was nearly impossible) so I seriously doubt is slipped...

I'm thinking vac or ignition/timing issue... the timing was slightly off already (was waiting to borrow a light, but was sounding good 'by ear'), and all of the wires were tight, but it was cold, so I wasn't going to bother with pulling the plugs (since a couple of them are difficult) at that time. Has new plugs (they were fouled) and wires (broke one of the cheap 5mm wires removing it).

Distributor looks good - and the starter is turning... belts are tight, but it did lose all power (maybe I have a drain somewhere...). I just went over rr tracks and on a very bad road when it happened. I don't think it's the alternator, since I couldn't get it running at all... besides, it was running just fine, and there's no way that many things could go wrong on this car at once : ) If I have it out, I'll run it down the street for testing, but I'm hoping it's some other kind of obvious (in heat and light) drain on the system.

No need to buy the harness! There is a "pigtail" from the engine wire harness to the knock sensor that is under ten dollars the connector is directly under the throttle body, comes out of the same harness loom that the injector connectors come out of.
The one I took out when I rebuilt was so brittle the insulation broke into pieces when I tried to bend it.
They very seldom go bad UNLESS they are subjected to physical shock, like being dropped. New they come wrapped in bubble wrap to protect them.
The sensor is made from a piezoelectric quartz crystal that is fragile but once installed fairly robust.
BTW That "Engine Wire Harness" price tag at the dealer is $1700!!!

In our case, the sensor itself was very brittle... the part that the cable connects into was almost completely separated from the part that screws into the engine... so I think there's a chance the sensor will need to be replaced. I did get in contact with another parts guy, and he told me he could get the wire for $10-$15 if I could get him the number off it. $170 for the sensor... I called about it when we first tore down, but at that price, it seemed worth it to try. I'm really hoping it's the wire... and that the continuity check is enough for the sensor (I just don't understand how that's testing it - I guess because I don't fully understand how the sensor works internally)


yeah - if buying the harness was really the only option, I was going to lowes and getting some wire... figured I could splice it in myself. No way was I going to consider replacing the engine wiring harness... that's just about insane!

oh, another thing... one of the pieces of the egr modulator was broken off when we towed it here (where the air line connects)... I 'fabricated' a fix for it, and it appears to be pretty good... but I'm wondering how sensitive this is, and if it could cause problems? My understanding of the basic functionality of the egr modulator says it won't be a problem, but I'm looking for advice at this point (this poor car : )

If the sensor body was coming apart, I would strongly suggest replacing it, as the internal component is very fragile when subject to external shock. There might be continuity but what if the dynamic response is degraded
by the broken housing?
I just checked my records the wire was $10.70 Toyota part number 82219-35010 Knock sensor wire.
This is for a 1992 V6 w/auto tranny.
The sensor piezoelectric puts out a VERY small voltage ONLY when it senses an approximately 7Khz "ignition knock", this is how it differentiates an ignition "knock" from other mechanical noises in the engine.
The only sure way to test it is to put it on a vibration table and ramp the frequency through it's operating range and monitor the output. I have been looking for a big old speaker woofer to mount my old knock sensor in and see if I really needed to replace it or if I wasted my money.
I have bought two wire harnesses off eBay BUT the Canada version uses water proof connectors through out they are useless to me. Just have to keep looking every week for this: (4 Runner,4runner)(wire,wiring)