Cel Code 13, 25, 26

[zlilz]

Hey, I had completed a major repair on my 91 ls400 about a month ago. The repair included a timing belt change, water pump change, fuel filter, replacing the rotors and caps along with cleaning the throttle body. All this I did myself.

The CEL lights up rarely. I have reset the ECU to capture the codes that apply to the problem. I have noticed the light only goes on when the car is slow (stop/go traffic, sitting at a light, starting the car) and most often when the engine temp is in the cool range. I have driven the car for a month and I get the following codes.

13, 25, 26

What could be the cause of this problem? Once the car is traveling 40mph or more, the light goes away.

[j.barleycorn]

Attached are some explanations for those codes. Unfortunately, a possible cause that is common to these three codes is skipping teeth on the timing belt, although it appears more likely to occur once the engine is warm, which is counter to what you say you are seeing...

dtc2526.pdf

troubleshooting_33_DIAGNOSTIC_CODE13_RPM_signal_circuit_no.2.pdf

[zlilz]

Actually, I had a little problem with the timing belt installation. I ordered a timing belt kit off ebay which consisted of OEM drive belt, timing belt, water pump and aftermarket idler bearings. Although the timing belt was oem and had the toyota sticker on it and everything, the only marking on the belt was the L cam, crank and a random dotted mark. I went to the Lexus dealer and they were nice enough to open a new belt and allow me to match up the crank markings and mark the L and R cam. My L cam marking was one tooth behind the original L cam marking on the belt.

Putting on the timing belt, instead of the white marks on the pullies, there were yellow dots on the pulley and the engine. I lined up the crank line, the R cam marking that I made matched up with the yellow dot. For the L cam, matching up the yellow dot on the pulley and the engine resulted in using the original L cam mark on the belt, not the cam mark I made. So I just put it on, assuming as long as the dots lined up, it shouldn't matter.

I rotated the crankshaft 2 revolutions and everytime, the yellow dot markings would line up, but the timing belt markings were always somewhere else. I tried this multiple times, each time resetting the timing belt, installing the tensioner then rotating the crankshaft. After 3 trials, I assumed it was suppose to be like this so I just started assembling everything.

Could I have actually advanced the L cam timing by a tooth? This car I bought and there were 2 owners before me. Since there were no white marks, I'm thinking the pullies might have been replaced for some reason by one of the previous owners. But it doesn't make sense that the cel light would light up when the car is traveling slow though.

[j.barleycorn]

I've never had the pleasure of changing the timing belt on my car, so all I know is from the tutorials. I assume you have seen this one on LexLS's most excellent site?

http://www.lexls.com/tutorials/engine/timingbelt.html#30

When you set the crankshaft mark to zero, did the camshaft pullys line up?

The marks you describe on the pulleys belt and the missing dot on the belt sound ominous. Wonder if the belt was really OEM, and/or was it for the right year? I don't know why you get the CEL at low speeds only, either.

Again, I am not an expert on LS400 valve timing. I suggest you do a search of the LOC on this subject and find the names of LOC experts and PM or mail them. Or, send LexLS a nice donation and speak to him directly!

Sorry I can't be of more help. Good luck!