Hi all, I am new to THIS forum, so I guess you can consider me a 'noob.' Over the past three years I have building a project Toyota FJ40 with a TPI stuffed under the hood. I purchased the motor with a harness and have finally fired up the motor this last week. I have been wiring and tuning and need some real expertise - and I can't think of a better source. The motor runs and pulls strong. However, the check engine light continually stays on after the engine is fired up. I tried using a friend's snap-on diagnostics reader, but for some reason, no codes were read. I have also attempted to do the self diagnostics mode by jumping terminals A+B without any luck. In fact, when I tried the self-diagnositcs mode, I hear something being acuated under the hood - and am not sure if this is normal...regardless, no flashing of the check engine light to indicate a self diagnostic mode. When I turn the key into the on position, the check engine flashes once, and then stays on constantly. Does anyone have any ideas on next steps to diagnose? Supposidley, this motor came out of a 92 Vette, and runs a MAP. Any help you guys lend would be uber appriciated.

You have installed all the sensors that are needed for the TPI.
You checked all connections so there isnt a bad connection somewhere ?
Try removing the battery for 30secs and fire it up again and see if the light still comes on.

Thank you for the help. As far as all sensors being hooked up - they are with the exception of the oil pressure switch for which I cannot find a connector on the Painless kit that came with engine. However, from what I have read, the fuel pump should not be coming on unless this switch is present - and the motor runs just fine without. My guess is that the previous owner wired around this.

I'll go ahead and try disconnecting the battery and see if this helps. My quesiton is - what would prevent the car from going into diagnostic mode? Also, when I jump terminals A&B at the PROM connection, I can hear something being actuated under the hood. Is this normal?

Thanks again for all your help - as this newbie learns more about TPIs

Correct the oilpressure sender activates the fuelpump, if no pressure is present it shutsdown the fuelpump. (maybe as you said this is bypassed)
When you cross the A-B terminal the fans shall go on (not heater, but engine cooling fans) maybe you dont have that connected and just an relay clicking ?!

What year are the prom from, VATS is disabled in the prom and you have bypassed the VATS system right ?

Theking,

Thank you for all of your insights. As you mention, I do think the oil pressure switch is by-passed, which in theory should not throw a code - otherwise the car wouldn't start. With respect to the fans turning on, I am going to have to look into that. From my understanding, the fans are activated by the ECM - by grounding out the relay - not supplying the swich power for this relay. At this time, the fan ground is not hooked up - so I don't think the relay is clicking. I'll spend some more time under the hood while I have my wife jump terminals A+B. I can more accuratley listen for what is being activated by jumping these terminals.

With respect to VATS - I have read much about this and believe that it is bypassed on this engine. It wouldn't run otherwise...right?

Thanks again for all your help.

Thats correct, if VATS not bypassed the car wouldnt even crank..
So its bypassed for sure..

Not sure if you get an SES error if the oilpressure sender unit is bypassed because there is no error code for bad sender unit (oil) but there is a change if it showing SES light anyway if it senses some errors in the circuit..
Im pretty sure that if you get the oilpressuresender installed the SES light will go away. had some problems with a short in mine, and the SES light came on sometimes, changed the switch and the SES light went out. maybe you have to plug it in to get rid of the SES light, will have a look at the painless wiring diagram tomorrow (gotta sleep now, going to work in ~7 hours) and help you out where to install the sender unit.

Take care

Thanks so much Theking! I'll dig through my painless book too to see if I can figure this out. Have a good night!

Theking --> BIG Thank you for getting me this far! I hooked up the fan ground relay and viola...the fan now comes on after jumping terminals A&B, and the computer DOES go into diagnostics mode. I have reset and rechecked it a number of times and it keeps throwing a code 54.

From all my litrature and online searching, this appears to be a low voltage fuel pump circuit. I am trying to follow the GM diagnostics flow charts and I have a quick question regarding the 'CKT' referred to in these charts. The instructions say to 'back probe' CKT 120. How do I find out what this CKT120 is for -- other than the obvious of following the wire -- which is heavily wrapped and hidden out of sight now.

dimkaPDX sorry for the delay, but had to do some overtime at work yesterday and I was so tired when i got home so I didint had the time to check the wiring.

You have used all of the connectors on the wiring ? or are anything loose ? the oilpressure unit is shall be located above the oilfilter and its maybe ~8cm long and has a (2pin) connector I think it was...

Have you measured the voltage at the fuelpump ? So you know its low ? but then the pump shuoldnt run good with low voltage..

The wiring diagram that I have dosent tell much about the oilpressure switch, it only says that it must be there , nothing more, will dig some more in this and get some info.

Hows its going for you, any luck yet ?

The oil pressure fuel pump switch is not required. It is wired in parallel to the fuel pump relay. And is designed to provide power to the fuel pump in the event the relay fails.

A properly working system will provide power to the fuel pump through both the relay and the oil pressure switch. It is not a cutoff device.

As for the DTC 54, low fuel pump voltage, the input pin to the ECM is either A20 ('7727) or E13 ('7730). Check to be sure that it actually has a wire and that there is 12+ volts on it when the fuel pump is activated.

RBob.

Thank you to everyone for all your help...this forum is PRICELESS. I wanted to close the book on this chapter in case anyone searches for similar problems in the future. As Theking and RBob suggested, the wire at E13 (which reads the voltage at the fuel pump) was cut for some reason. I hooked it up to the positive lead on the fuel pump, reset the ECU by pulling the in-line fuse, then restarted the vehicle. No more check engine light...for now.

Again, thank you for all your help!

glad to hear it worked out for you

Not to hijack the thread, have a quick question though. My electric fan was replaced with a mechanical fan. My SES light has been on forever and I'm unable to do diagnostic. SES just comes on when I turn on the key and never blinks or anything. So it was mentioned here about the fan ground not being hooked up causing the SES light to short out. Would I be able to just jump the two wires of the fans hookup or is there some other way I need to set it up?