95 S/C Previa keeps blowing EFI Fuses....


98 SNAKE EATER
06-04-2005, 09:18 AM
This morning I started her up, drove a few miles from home and the motor shut down :eek7:


Checked all the fuses and the EFI fuse (15A) was blown....

Replaced it and it blew instantly...

Put a 20A in and it ran for about 10 minutes before blowing again...

Tried a 30A (it was all I had left) and that got me to my driveway before blowing again....

I'm guessing the Fuel Pump might be shorting out, but before I start working on it, I just wanted to know if it was a common problem among Previa's?







Rick

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lisamac
12-17-2005, 01:57 AM
Sir I am having the same problem and have been trying for days to find that short. I would geatly appreciate your help if you can lead me to the problem.

Thank You and Merry Christmas

Tom







Rick

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98 SNAKE EATER
12-17-2005, 09:54 AM
Hey Tom,

The problem turned out to be the wiring harness for the O2 sensor...

The harness also carries a main lead to the fuel pump and the exhaust melted it, causing a short....

After rewiring it properly, sealing it with heatshrink and routing it away from any exhaust heat, she's been running perfectly eversince :smokin:




I found out that this was a common problem among Previa's, Supra's, 4-Runner's and Land Cruiser's...





Rick

lisamac
12-18-2005, 04:44 AM
Hi Rick
I appreciate you coming back, I look at both of the sensor one in front of the converter and to its rear. One of them has 4 wires which I presume its the Heated one.look around it but its still on its clip and far from the exhaust. Perhaps its grounded in the harness. If the sensor should go bad will it still blow the fuse.I even disconnect the both,and tried again and still blows. The wire you are talking about that's tied in with the pump what is the color. I don't even hear the pump when I turn it On. or Power at the Battery pin at the check connector. By the way will this problem also will cause No Spark at coil If you got more for me to know, please help I need to make this van operate so I can go get the kids something for christmas.

Once again Thank You very much and Merry Christmas

Tom

98 SNAKE EATER
12-18-2005, 10:41 AM
Hi Rick
I appreciate you coming back, I look at both of the sensor one in front of the converter and to its rear. One of them has 4 wires which I presume its the Heated one.look around it but its still on its clip and far from the exhaust. Perhaps its grounded in the harness. If the sensor should go bad will it still blow the fuse.I even disconnect the both,and tried again and still blows. The wire you are talking about that's tied in with the pump what is the color. I don't even hear the pump when I turn it On. or Power at the Battery pin at the check connector. By the way will this problem also will cause No Spark at coil If you got more for me to know, please help I need to make this van operate so I can go get the kids something for christmas.

Once again Thank You very much and Merry Christmas

Tom


Tom, I'd try tracing the power wire from the fuel pump and then work my way back through the harness....


Have someone cycle the ignition while you check the main lead with a test light....


The EFI fuse wouldn't cause a no spark condition (that's the IGN fuse), so you might wanna check if the distributor has pulse as well....







Rick

lisamac
12-18-2005, 10:27 PM
Rick

Here's what Ive done so Far:

1.I've to power the pump by using direct power from the battery in order for it to operate. I did this in the beginning and it starts right up.don't understand how it starts up without the EFI fuse.I did this twice,then finally it just gave up. Look for spark at coil, Nothing there,also the Injectors for clicking,Nothing..

The Circuit Opening Relay has to operate before gets to the pump. I check the Main EFI Relay and C/O relay checks out Ok. Also the Battery Pin at the Check Connector is w/o power when it suppose to when key is in On position.

Does it have a Fuel Pump Relay? Another site says the pump is the common problem with Previa's, Supra,Celica's. I question this common problem. If its the pump why is it operating when using the battery to energize the pump.

When I put a test lite across the EFI fuse it doesn't come On,meaning its not shorted.But it comes On when I put key in On-also when I remove the Ign fuse the lite turns Off.

It seems that the Ign circuit is creating this problem. The Ign circuit gives power to the Coil,Ignitor,Injectors thru the Black and Red wire. and activates the EFI main relay giving power to Black and Orange wire thatgoes to the C/O relay,Engine oil level relay,Fuel press. up solenoid,IACV,and Heated Oxygen sensor. Before the pump operates it has to come from the C/O relay to get to the pump.However when the EFI fuse blows it will never power the C/O relay.

Well Rick, Thanks A lot if you got any other ideas am willing to listen and learn,Thank You Again I really appreciate it.

Tom

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