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Discussion Starter #1
The OD/OFF light starts blinking continuously, like an indicator light, after driving some 5 - 10 km. The car sometimes appears to jack on engaging D or R gears. Acceleration looks ok. Any suggestions to solve the problem, please
 

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This is where I would start:
Right now, I think a flashing O/D Off light indicates the Rav4's computer is throwing a code for the tranny, indicating a transmission system malfunction. Your 1997 Rav4 is either OBD1 or OBD2. If it is OBD2, get a code reader and follow its instructions. If OBD1, read the codes using the procedures at the following sites:


If your Rav4 is OBD1, and the above procedure does not give any codes, then try shorting terminals Tt and E1 (instead of TE1 and E1).

For OBD2 codes, most likely the code will be a P07--. (Starts with a 7.) For help interpreting the OBD2 codes and fixing the problem, see DIAGNOSTICS - 1996 RAV4 | Free Download . Typical causes are a bad shift solenoid, low transmission fluid, and similar.
 

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Discussion Starter #3
Hello, How do I tell whether the Rav4 is OBD1 or OBD2 and where is the connecting port located in the car?
 

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The OBD1 connecting port is known as "DLC1" in the service manual section that I Iinked above. I think "DLC" stands for "diagnostic link connector" or similar. Do a search of the service manual section for DLC1, and you will see drawings that show the location and some other help using this connector. The youtube video I Iinked above also shows the location within the first five seconds or so. The photo below also shows DLC1, circled in green:

(Thanks to Mick Hatzo for putting this photo in his album.)

Here's a site that gives the procedure for getting the O/D Off light to blink out the codes on a Camry, using the DLC1 connector: 91 camry OD light blinking. This procedure may work on your Rav4 as well.

In the service manual, the OBD2 connector is called "DLC3." Search the above linked manual section for DLC3, and you will see drawings showing its location in the driver/passenger area, near the driver's right knee on left-hand-drive Rav4s.

You can google for ways to tell OBD1 from OBD2. But if the DLC3 (OBD2) connector is absent, then I would conclude that your Rav4 is OBD1.

Again, this is just where I would start. I have not been able to confirm that this is the way to get the codes that are causing the O/D Off light to blink on a 1997 Rav4. But I do see many reports on the net for 1990s Toyotas that, for a flashing O/D Off lamp, and to retrieve codes --
-- for OBD1, use the DLC1 connector terminals Tt and E1.
-- for OBD2, use the DLC3 connector and a code reading tool.
 

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Discussion Starter #5
I checked the car thoroughly and I can conclude that the rav4 is OBD1. When I applied the OBD1 diagnostics yesterday by shorting terminals TE1 and E1, and reading the check engine light as described at troublecodes.net, I noted that the trouble code is 21, which points to the Oxygen Sensor.

There seems to be a good relationship between the finding and current behavior of the car. The fuel economy really worsened in the last six months, sometimes the car jerks on engaging R and D gears and car hesitation is not uncommon.

I have seen some videos describing the replacement of the oxygen sensor. but it appears there are two oxygen sensors, so I don't know which one to tackle. Otherwise, this is a big step and thanks a lot.
 

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OBD1 Code 21 is for the front (= upstream) oxygen sensor. "Upstream" refers to the sensor being upstream (relative to the exhaust gas flow from engine to exhaust pipe) of the catalytic converter. The upstream sensor is located physically higher than the downstream sensor. Drawings of the sensor are shown on pages EM-34 and EM-63 of the manual at ENGINE MECHANICAL - 1996 RAV4 | Free Download . Also for the Rav4.1.1 (meaning 1996-1997 Rav4s), the upstream sensor is mounted on the Rav4's exhaust manifold with two nuts (12mm?). The downstream sensor has no nuts.

Note: The Rav4 3SFE engine has only one "bank" of sensors. For Code 21, you want to replace "Bank 1, Sensor 1" (not Bank 1, Sensor 2).

Before replacing the upstream sensor, check that the electrical connector is correctly attached. If, say, someone was working on the engine recently and disconnected the sensor, then this person may not have re-connected the sensor correctly. I have made this mistake myself.

I would buy a Denso oxygen sensor. Denso makes many of the parts for Toyota and Honda. Put your Rav4's information in at densoautoparts.com to find the part number for the Denso sensor. I think it's Denso part number 234-2058. Get the "OE Style" Denso sensor. If you buy the Denso oxygen sensor online, try to get some assurance from the seller that it really is a Denso sensor. This is one part where I have seen a seller sell a counterfeit Denso sensor. I have read reports of same from other people.

You might want to buy a can of PB Blaster, spray it on the two (12mm?) nuts; run the Rav4 for a few minutes; and let it sit for an hour. The PB Blaster breaks corrosion and rust down so that freeing bolts, sensors, et cetera is easier. Any steel bolt or nut exposed to exhaust gases may be especially hard to free. But the PB Blaster makes a huge difference. Also if you can warm up the engine before trying to free the nuts, the warmed up nuts will free more easily. Just be careful of the hot engine parts. Wear leather gloves.

After the engine is warmed up is when a failed upstream oxygen sensor will cause poor running. Could it cause the O/D Off light to blink? I could see the bucking from a failed oxygen sensor causing automatic transmission problems. No guarantees. It might be worth shorting DLC1 terminals Tt and E1, and taking the rest of the steps at 91 camry OD light blinking to see if the O/D Off light will blink codes for you.

The torque on the two (12mm?) nuts is 14 ft-lb.

After replacing the oxygen sensor, you have to clear the code. There are a few ways to do this. Disconnecting the battery for five minutes (or one minute?) is one way.

Lastly, I see your Rav4 is in Uganda? There are some variations in Rav4s from one country to another. I cannot guarantee the resources above will work for your Rav4. But they are where I would start.

Is your Rav4 a two door or four door model?
 

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Discussion Starter #7
The rav4 is a four-door model imported from Japan. I repeated the procedure yesterday using terminals E1 and TE1. The check engine light revealed a code of 21. But also the OD OFF light was blinking and revealed a code of 44. At troublecodes.net, only the check engine light was applied to relate the code to the potential issue. I dont know whether the blinking OD OFF light is telling something more. I shall also use
terminals Tt and E1 and see whether I get more trouble codes.
 

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Did you triple check that the light flashes 44 times (and not, say, 42 times)? Code 42 seems to be more common.

This site gives blinking "o/d off" codes, but not necessarily for the DLC1 connector: Error Codes TOYOTA & SELF-DIAGNOSTICS . It says Code 44 is the speed sensor (or rear output speed sensor).

Elsewhere Code 42 is also said to be the speed sensor.

If you google on {symptoms bad speed sensor}, you will find sites that list symptoms like you describe.

The following is the only early 1990s Toyota manual I could find that gives more detail on transmission codes: A140E AUTOMATIC TRANSAXLE - 1994 Camry | Free Download . It has a slightly different procedure, starting on page 44, for reading the tranny codes when the o/d off light is blinking:

O/D OFF Blinking Light, 1994 Camry
DIAGNOSTIC TROUBLE CODE CHECK
1. Turn the ignition switch ON, but do not start the
engine.
2. Push in the O/D main switch to ON.
HINT: Warning and diagnostic trouble codes can be
read only when the O/D main switch is ON. If it is
OFF, the 0/D OFF indicator light up will light continu–
ously and will not blink.
3. Connect terminals TE1 and El of the
DLC1.
4: Read the diagnostic trouble code indicated by the
number of times the O/D OFF indicator light blinks.
HINT: If the system is operating normally, the light will
blink 2 times per second.

If it is the speed sensor, then here are the part numbers:
Speed sensor, auto tranny, 4wd part number 83181-12020
Speed sensor, auto tranny, 2wd part number 83181-12060

Some clues on the location of the speed sensor: Speed sensor location/access, 99 Rav4 auto
 

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Discussion Starter #9
Using
terminals Tt and E1, the engine check light did not blink at all. The OD off light also did not blink at all.

When I used terminals TE1 and E1 again, I got the same blinking codes as earlier before. I am now embarking on working first on the oxygen sensor, after which I will perform another check.

Many thanks for sharing the useful information.
 

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Discussion Starter #10
I did change the oxygen sensor, which cleared trouble code 21 retrieved from engine check light.

How many speed sensors does the first generation rav4 have? I also changed the speed sensor located on top of the transmission, but trouble code 44 (from OD/OFF blinking light) was not cleared. It continues to blink after driving 3 to 4 kms. When you turn of the engine and restart after say 10 mins and then drive for more several kms on a freeway, the OD/OFF light starts blinking again. I have not found any interpretation of trouble code 44 (from blinking OD/OFF light) retrieved using DLC1 diagnostics. Anyone there with this information?
 

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This site says Code 44 for the 1994 Camry is for the overdrive solenoid:
 

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Discussion Starter #12
In one of the trouble code identification for rav4 based on OBD1 diagnostics, I found out that code 44 displayed by the O/D OFF warning lamp refers to: transmission output shaft speed sensor 1 rear malfunction. According to the diagram of the engine compartment, there are 2 other speed sensors namely; vehicle speed sensor (combination meter) and vehicle speed sensor (front). The diagram is not very clear through. Now I need to locate
transmission output shaft speed sensor 1 rear, for replacement.
Anyone, please help locate it.
 

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From looking at the manual, my Rav4 is different, the Rear VSS, the EGR VSV and the Knock Sensor share a common splice point.
From under the car, looking up at the back of the engine, find the knock sensor and follow the wires.
 

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Discussion Starter #14
I am able to view what appears to be the transmission rear output shaft speed sensor, from the front right-hand side bottom area of the car. It is located at the back of the engine. However, I observe that it is located at a point with very restricted access. My hand can bearly fit within that area making it extremely difficult to remove and replace. Are there any special steps to be taken to replace this speed sensor? If at all this speed sensor can be replaced through simple procedures, why would Toyota fit the sensor in such a restricted location? Which components do you have to remove before properly accessing this speed sensor? Any ideas, please?
 

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Discussion Starter #16
I was a bit confused by that service manual. According to this diagram from the same manual, showing the engine compartment, Item 10 is the vehicle speed sensor (combination meter), Item 11 is the Vehicle speed sensor front (transmission front output shaft speed sensor) on the A540H automatic transaxle. These speed sensors (10 and 11) are easily reached and replaced after removal of the air cleaner assembly.

Now, item 24 is the vehicle speed sensor rear (transmission rear output shaft speed sensor). This is the speed sensor I talking about. While I can view it as described earlier, it is hardly reachable for removal and replacement, in a simple operation.


1999 RAV4 Engine Diagram.png
 

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My 99 Toyota service manual list 2 automatic transmissions, one has the rear VSS under the air-cleaner(A540H) and the other model has the rear VSS under the car(A247E).
I have a manual transmission and don't know anything about the automatics.
 

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Good point. I assumed that the original poster had the A540H transmission. 4WD automatic models have this transmission, while 2WD automatic models have the A241E one.
The parts-locating schematic could probably be covering all bases by indicating every possible component (manual, automatic, 4WD and 2WD).
The speed sensor on the A241E transmission can be accessed by removing the plastic engine under cover.
Is it possible that the sensor you cannot remove is something else? Could you post a picture of it for reference?
 
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