Korey

Posted this in another forum, but just wanted to see what anybody here had to say regarding this. My CE light comes on usually when I start moving, then the truck bogs down. I jumped the diagnostics box with a paper clip to see what the code was and it gave me this: 1 2 5 2 OR DOT DOTDOT DOTDOTDOTDOTDOT DOTDOT. Anybody know what this code is? Thanks in advance.

I've lurked through here several times, but this is my first post here.

bugs1961

Welcome!

You can download the FSM here: http://www.ncttora.com/fsm/index.html

The '90 to '95 4Runner manual will cover the engine and codes. EG2 chapter, MFI section has the codes and troubleshooting information. In my PDF download, it's on page 1018.

Toyota used 2 digit codes in this era so you probably have two codes: 12 and 52.

12: RPM signal from the distributor not received by the ecu for 2 seconds.

52. Knock sensor signal not received by the ecu.

The FSM will guide you through the troubleshooting to determine what the problem is rather than replacing parts until the problem goes away. Saves a lot of money that way. Take care and have a great day,
Bugs

Korey

Thanks for the link to the manual. Gonna look into it and tackle the problem now!

Korey

I went ahead and tested the TPS. All terminals were within range except for IDL-E2 which was out of range (showed an infinite amount), so I tried to adjust it without much success because no matter how slow I moved the TPS, the numbers were inconstant and I tried for about five hours before calling it a night. Once I get this fixed, I will post a reply for further reference. Sorry it took so long for me to reply to this post.

Korey

So I got a new TPS, thinking that since everything but IDL-E2 was within range, the new one would fix the problem and make it easier for me to adjust. It's doing the exact same thing. Numbers jump all over the place between infinity and 100 even when I'm not touching it and since the specs call for the IDL-E2 adjustment to be under 2300, the best I could do was tighten it down while it gave a reading of 100, or .01 as shown on my tester. Here is a pic of how I have it set up, so any help would be appreciated cuz I've been trying to tackle this problem for over six months now.

Korey

Guess what- I dug into my service records to see if the knock sensor or wire was replaced when I had the head gaskets installed and the wire was indeed replaced, so I doubt it is the wire especially since it was done almost two years ago by an experienced mechanic who's hobby is wheelin these trucks.

So I looked around the engine while it was running and noticed one of the spark plug wires shaking, so I pulled the wire, and the plug was indeed loose! People have said they heard a slight ticking noise coming from the engine. However, the CE light still comes on when the throttle hits about 2500rpms, but at least code 12 went away. Now it's just code 52 which means I am at least making progress. It still idles fairly high on start up even when it's been off for just a few min which means the knock sensor is probably advancing the ignition. Any more theories?

TheRival

Are you positive that when testing the 4 prong TPS that you are not testing backwards. The image in the FSM is a cut through from the top. not a view from the bottom. this would cause you to be testing everything in reverse! I spend hours trying to figure that one out... went out and purchased a new TPS only to have the identical problem trying to set it. Once i realized my error, i set my old tps and returned the new TPS to get my $100 back.

just a thought...

Korey

Pretty sure I did it right. Went over it so many times to make sure. MPG is down to less than 10!

Korey

Realized that I never followed up on this thread, so here I am. One day almost a year ago, the check engine light all of a sudden went out and the power kicked in. No more code 52. I don't know what the heck it was, and why it would go away all of a sudden. It was shortly after the time I started adding Star Tron to the fuel for increased performance and MPG which helps keep the engine clean from ethanol. What a difference. Don't know if this would be related but it'd be interesting to see if anyone had the same experience with code 52 and Star Tron.

The light did come back on a couple of days later, but it was the code for the oxygen sensor which I assume is bad cuz I had been driving the truck with the code 52 for about two years which I'm sure messed up the sensor from the mixture caused by the knock sensor circuit. I haven't replaced the oxygen sensor, but it gets great MPG even with the light on. I'm getting 17 MPG in local driving right now. When I replace the sensor, I will replace it with a denso unit.

Benji19912wdsr5

I've been running with the problem you describe since 2005. Thankfully, I generally put on only about 1,000 yearly since. Recently replaced all the good stuff--timing belt and all belt rollers, water and oil pumps, valve adjust, knock sensor and wire, front camshaft and crankshaft seals. Still getting code 52, except that sometimes I get a hard miss and the CE lite goes off as power snaps back. I get strong power just long enough to feel it cause as soon as I move the accelerator a little, the lite returns and performance drops. I'm checking the wiring connectors behind the glove box, then checking my timing and the distributor integrity.

It's not a crawler, but at over 324k and lots of highway miles, this one is still lots of fun.

Korey

Old threat, but I am happy to report code 52 never came back although I do have code 21, which is the O2 sensor. This came on after my mechanic put on a NGK sensor. LOL. I picked up a new Denso sensor a couple years ago but never got around to putting it on... Still can't figure out why I got code 52 after I had the head gaskets done around 2008 years ago and why it went out! Any updates on code 52? It sure has been a while!