2 Trouble Codes: Code 41 (Throttle Position Sensor Signal) & Code 43 (Starter Signal)

[ToyotaVanNut]

Hi there,

The check engine light is on in my 1991 Toyota Previa (no turbo). I stuck a paperclip in the Diagnosis Data Link Connector 1 (DLC1), TE1 and E1 (using this video https://www.youtube.com/watch?v=lEZ9Gl53DhQ), and I am showing two diagnostic codes, 41 & 43.

The Chilton guide says:



Code 41: Throttle Position Sensor Signal — "Open or short detected in throttle position sensor signal (VTA) for 0.5 seconds or more."
Code 43: Starter Signal — "Starter signal (STA) is not input to ECU even once until engine reaches 800 rpm or more when cranking."


I have no experience with either problem. Can anyone recommend a plan of action for solving these issues? The van runs fine, I just need to pass California smog.

It seems like there is a way to adjust the throttle position sensor signal, but would an adjustment solve the issue? I have next to no plan for the starter signal. My van philosophy is repair first, but if repair on either of these is too involved, I am happy to replace the part(s). If that's too involved, I am happy to take the vehicle somewhere.

Thanks for any help.

[Ian R.]

Hey TVN, I have a 1988 van but it had the code for 4-3 for the last 8 years ( same code and error description in the service manual, but no description on how to repair). Until I saw that the fuse for labeled starter in the fuse panel was blow. I replaced it and reset codes and the error was gone. I don’t know what the fuse does exactly as my van started up and ran fine. If nothing else it may be a place to look. Here is the post I made on it https://www.toyotavantech.com/forum/showthread.php?8308-1988-1989-code-4-3-Starter-signal

as for the TPS code (for vanwagons at least) usually means it needs to be replaced. But the replacement may be entirely different for vanwagons. I would wait to hear if someone can point to a thread about that.

ian

[John Kaufmann]

Hi there,

The check engine light is on in my 1991 Toyota Previa (no turbo) . . .



Code 41: Throttle Position Sensor Signal — "Open or short detected in throttle position sensor signal (VTA) for 0.5 seconds or more."
Code 43: Starter Signal — "Starter signal (STA) is not input to ECU even once until engine reaches 800 rpm or more when cranking."


I have no experience with either problem. Can anyone recommend a plan of action for solving these issues? The van runs fine, I just need to pass California smog.

It seems like there is a way to adjust the throttle position sensor signal, but would an adjustment solve the issue? . . .
You did not say how many miles, but you did say it's 32 years old, so is a prime candidate for the TPS wiring failure if the TPS harness has never been fixed. As you know, there is a bit of rocking of the engine in operation (that's why the flex pipe), and the TPS wiring is tight enough to cause fatigue of the wires, with eventual circuit opening, at the TPS connector. Since the van runs fine, the easiest way to check that is to open the left-side access hold and flex the harness while it is idling. If it stumbles, you have the connector wiring issue, and it will eventually refuse to run.

Since the problem occurs in the connector, the only practical fix is another connector -- with enough harness on it (at least several inches) to patch into your harness. Then you cut your harness at the connector and patch in the replacement connector with solder and heatshrink tubing. The only practical way to get that connector is attached to another TPS (NOT from a Previa, because of this design weakness), from a junkyard or, sometimes, online (like eBay) if the seller has removed it with harness attached.

Fortunately Toyota used that TPS (89452-12040) a lot -- 90-94 Tercel, 86-91 Corolla, 84-95 MR2, 89-93 Celica, 88-91 Camry and Lexus ES250, all Previas (but avoid), 88-95 4Runner, 92-98 T100 (where I got mine). As you live in the land where cars don't rust out, you should be able to find one of those at a yard. The wire colors will probably be different, but you can match up the wires by connector position. Now that you have added enough to the harness to ease the strain, you should probably run some tape around the harness to protect the connections.

[ToyotaVanNut]

Hey TVN, I have a 1988 van but it had the code for 4-3 for the last 8 years ( same code and error description in the service manual, but no description on how to repair). Until I saw that the fuse for labeled starter in the fuse panel was blow. I replaced it and reset codes and the error was gone. I don’t know what the fuse does exactly as my van started up and ran fine. If nothing else it may be a place to look. Here is the post I made on it https://www.toyotavantech.com/forum/showthread.php?8308-1988-1989-code-4-3-Starter-signal

as for the TPS code (for vanwagons at least) usually means it needs to be replaced. But the replacement may be entirely different for vanwagons. I would wait to hear if someone can point to a thread about that.

ian

Thanks very much, Ian! I will give this a shot for sure and try to report back with the result.

[ToyotaVanNut]

You did not say how many miles, but you did say it's 32 years old, so is a prime candidate for the TPS wiring failure if the TPS harness has never been fixed. As you know, there is a bit of rocking of the engine in operation (that's why the flex pipe), and the TPS wiring is tight enough to cause fatigue of the wires, with eventual circuit opening, at the TPS connector. Since the van runs fine, the easiest way to check that is to open the left-side access hold and flex the harness while it is idling. If it stumbles, you have the connector wiring issue, and it will eventually refuse to run.

Since the problem occurs in the connector, the only practical fix is another connector -- with enough harness on it (at least several inches) to patch into your harness. Then you cut your harness at the connector and patch in the replacement connector with solder and heatshrink tubing. The only practical way to get that connector is attached to another TPS (NOT from a Previa, because of this design weakness), from a junkyard or, sometimes, online (like eBay) if the seller has removed it with harness attached.

Fortunately Toyota used that TPS (89452-12040) a lot -- 90-94 Tercel, 86-91 Corolla, 84-95 MR2, 89-93 Celica, 88-91 Camry and Lexus ES250, all Previas (but avoid), 88-95 4Runner, 92-98 T100 (where I got mine). As you live in the land where cars don't rust out, you should be able to find one of those at a yard. The wire colors will probably be different, but you can match up the wires by connector position. Now that you have added enough to the harness to ease the strain, you should probably run some tape around the harness to protect the connections.

Thanks very much for your thorough reply, John. As for milage, the Previa is currently sitting at ~187k. I'll definitely give this a shot. Do you mind elaborating on what you mean by the "left-side access?" Will try and report back if this ends up solving the problem and if the code goes away.