swamprunner1

This is a 88 pickup w/22re. I just rebuilt the motor and can't get it to run right since putting it back in.


I've searched the forum but there is not mention of my particualar problem

I keep getting code 52. I have a known good KS in the block. I've traced everything back to the ks wire being grounded at the computer. I cut the wire right after it came out of the pig tail so I know the shielding isn't grounding the wire.

MY QUESTION IS...WHAT IS CAUSING THE WIRE TO BE GROUNDED AS IT COMES OUT OF THE ECU?

I have to fsm and neither of them mention the knock sensor or how to test the circuit. From what I've read on the board the wire should not be a ground just the sheilding around it.

I was also having tps problems which seem to go hand and hand with the ks.
I put a new tps on and it seems to be working fine now b/c I'm not getting that code any more.

The only other thing I can think is that the timing may have some thing to do with it but it pretty much dead on. The weird thing is that the distributor is rotated all the way counter clockwise within the adjuster nut limit. On every other 22re I've had it been close to the middle of adjustment. I check to see if the dist. was tooth off but it seems good to me.

Any help/ideas would be greatly appreciated. I've spent countless hours trying to figure it out and it has me stumped.

isaac338

Have you tried using an electrical connection tool (or a tiny screwdriver or dental pick) to remove the wire entirely from the ECU connector, and then running a new temporary wire to see if it goes away?

I dunno if you've ever done that but the wires have a metal connector crimped onto the end of them and then they clip into the plastic connector which connects to the ECU, so you can push the little clip down and remove the wire and metal crimp from the connector.

BT

If the ecu is causing the ground, the ecu could be the problem. If the 22re is like the 3vze, the code means no KS signal is making it back to the ecu, which could mean an open, maybe bad contacts or a broken wire. But if you're certain about the ecu shorting to ground, sounds like a faulty ecu.

swamprunner1

Forgot to mention I've tried another ecu and got the same result...so its highly unlikely its the ecu.

The ks wire is good and so is the connector.

Just to be sure I tried running a new wire from the ks to the ecu where I cut the original one. Still the same out come...grounded

I haven't tried removing the wiring...but I know if I remove the pigtail from the ecu the wire is no longer grounded.

DOES ANYONE KNOW A WAY TO FOOL THE COMPUTER or WHY THE ECU IS GROUNDING The KNOCK PIN?

isaac338

Is the knock sensor wire pin on the ECU grounded?

BT

You've only got 3 options in that circuit: The knock sensor, the wire (including the pig tail), and the ecu. There's nothing else to fail.

If you can get another KS, you could try hooking it up with a new wire all the way from the ecu to the sensor.

It has to be one of those 3 bits.

sb5walker

I wasn't aware they were shielding the ks wire back in 88, I thought it was later. So, learn something new every day.

The code can come either from an open circuit or a short circuit. If a wire is damaged through pinching, the inner wire can be shorted to the shielding, and the wire will still have good continuity but will fail due to the short. Easy to test for continuity between inner wire and shield - should be none.

If you need new shielded wire, this aircraft supply place sells excellent MIL-spec 16AWG wire in 10' sections for $6 which is a very good price:
http://www.aircraftspruce.com/catalo...shieldwire.php

As far as the ecu is concerned, there is only one ks wire, which is powered by the ecu and grounded to the block by the sensor when it detects a ping. If the sensor were bad, it might either never ground the wire or be shorted to the block full time.

Check the last few posts in this thread - some good info that may be of some help:
http://www.toyotanation.com/forum/sh...56#post2932051

swamprunner1

I've tried 3 different knck sensors and they are all good on other trucks.

The pin on the ecu must be grounded b/c when you unhook the pigtail the ks wire is not grounded.
I snipped the wire about an inch out of the pig tail...if the pig tail is plugged in the wire is grounded if not its not grounded. I did this to make sure the wire wasn't shorted to the sheilding.

WHAT CAUSES THE KNK PIN ON THE ECU TO BE GROUNDED?

There has to be something else in the ecu triggering it to ground b/c I've tried another known good ecu and they both have the ecu pin grounded.

I guess my next step should be taking the ecu out of this truck and trying it in another truck to see what happens. I'll have to find that truck first b/c my other truck is a turbo so it won't work there.

Lumpy

When mine was acting up it was a bad splice in the wire coming off the sensor just in the harness... Maybe this for you as well???

abecedarian

Keep in mind that checking the resistance of the wire when connected to the ECU will also be checking the resistance / impedance of the circuitry within the ECU and it will ultimately be grounded somewhere.
I would recommend replacing the entire knock sensor wire from the ECU out and check for continuity between the center conductor and shield prior to connecting it.

BT

If you're checking an inch after the pigtail, the pigtail could be the problem. When mine threw a 52, it was because of the connector.

swamprunner1

I guess I need to check the pin in the back of the ecu. Hopefully its not grounded b/c that leaves only the knk connecter in the harness to be the culprit.

Still can't believe it can be this hard...It's only one wire and 3 connections.

shaeff

Tricking the ECU isn't the answer. Test for continuity between the shield wire and the signal wire for the KS. If there's continuity, the wire is bad. Even if there isn't, that doesn't mean that the wire is necessarily good, either.

Rewire the knock sensor. Get a new connector from Toyota (I'm fairly certain it's the same as the 3vz's, but can't remember off hand). Do the rewire properly with a new connector and new wire right up to the ECU, and get back to us.
Right on.

sb5walker

swamprunner1, in re-reading this thread, I think abe has put his finger exactly on the problem. You keep saying "the wire is grounded as it comes out of the ecu", and I sort of glossed past that on first reading. On second reading, I finally caught it, and thought: 'how does he know that?' I realized you must be trying to do some kind of continuity test between the knock sensor lead and a ground. For the reasons that abe mentioned, this will not work.

In order to test resistance or continuity, a multimeter inputs a voltage into a circuit to see whether and how much current flows. So you are actually inputing a voltage into the ecu, on a wire that normally only ever sees ground or open circuit (the wire is briefly grounded by the knock sensor when it hears a ping, and the ecu detects the flow of current). First of all, running a voltage into an electronic device that has IC chips is a very bad idea - you could easily damage it. Whether you have damaged those ECUs depends on how much voltage your multimeter applies: older or cheaper meters may use higher voltages that may cause damage. Secondly, as abe pointed out, it won't work because the circuit has a bunch of electronic components connected together in a living circuit that includes grounding. To test any of those components, you would have to remove them from the ecu to test them individually, and that STILL wouldn't tell you whether the circuit were internally grounded.

Basically, it sounds like you were running a test which doesn't need to be run, which doesn't tell you anything, and which stands a good chance of burning out the knock sensor circuit in the ecu.

So are you still getting a code 52?? If so, as BT said: 'You've only got 3 options in that circuit: The knock sensor, the wire (including the pig tail), and the ecu. There's nothing else to fail.'

The only testing for ground you need to do (and can possibly do) is the wire itself. You can check for ground on that wire by disconnecting it from the ecu and knock sensor and attaching one lead of the multimeter to a chassis ground and the other to the knock sensor pin in the harness side of that connector. There should be no ground. Also, IF the knock sensor wire is shielded (is it?) you can look for continuity between the shield and the center wire. Again, there should be no continuity. Finally, attach a long test lead to one end of the ks wire, and look for continuity between the other end of the wire and the test lead. You should have continuity. If you pass those three tests, the wire is not shorted or open, and that's a good thing. It still might be receiving inductive interference if it runs close to something like an ignition or injector wire, and if the ks wire isn't shielded, or if the shield isn't grounded, but at least you'll know the wiring doesn't have any faults.

Then if you still get code 52, it's either bad ecu (possibly damaged by trying to test it for continuity to ground), or bad knock sensor, or knock sensor not grounded to block, or some small chance if the wire isn't shielded that it could be receiving inductive interference.

swamprunner1

Been busy so I haven't had time to mess with this. I'm gonna re test everything today and go from there. I will post up what I find.

Thanks for all the input guys.

Matt

Sanchez

Heya Matt... I have been having an identical problem on a '91 3vze, I would be interested in hearing what you figure out... Until then, time to get into it further.


Tim

swamprunner1

The wire is good. There is continuity from pig tail to pig tail.

There is no continuity from the sheilding to the wire so that good.

The knock sensor is good.

I have tried to different ecu and they both give the same result. I doubt that both computers are bad.

So back to square one???????????????

sb5walker

And what result is that? Are you getting code 52?

swamprunner1

yup,
Code 52..

At this point I'm just gonna drive it and not worry about it.

shaeff

^You'll experience timing retard (power loss), enriched fuel mixture (bad gas mileage), and possibly some sputtering at wide open throttle, due to the timing retard.

There are only THREE things that cause code 52, in order of most common to occur:

1) Bad wiring. This is usually the case.
2) Bad knock sensor.
3) Bad ECU.



Late edit to clarify a statement I made above- the enriched fuel mixture is a byproduct of timing retard, not something the ECU does specifically.