afm and tps dtc wont go away

[fourstars]

Been searching multiple websites including this one and no luck with my issue.

92 Lexus SC400 1UZ to a 86 Toyota 4Runner

Almost finish this swap and now having some issues. Motor starts up and revs good. It’s getting everything it needs but it has 5 DTC.

7: TPS

29: Right 02 sensor

31: AFM

32: AFM

41: TPS

Tested all wires to the ECU and everything is connected and my multi-meter beeps every time. Switch out a new AFM and still same codes. Disconnect the sub TPS for TRAC control and still same codes. I did not modify any wiring related to TPS and AFM. O2 sensor I did touch and less concern about that DTC. The code 7 is not to be found on my FSM, Im not sure why Im getting that DTC. I’ve search further and found it on a few sites as an issue linked with TPS. Am I overlooking something here?

I was told or read the 92 1UZ with TRAC control can cause a few problems. But I have also read it was more of just wiring issues. So, I am not sure what to do. Should I get a new ECU? I don’t really want to spend more cash if I don’t have to. I bought a complete running Lexus SC400 and it drove well with NO check engine lite. Please help direct.

 

[pajman]

It could be an earhing issue , have you bonded the motor to the frame. Also I think there is a sensor circuit earth that has to be seperatly connected to an earth on the the main loom. There are lots of guys on here with alot of knowledge so hopefully they can help . I had a few codes on mine and found one missing wire was the culprit.

 

[gloverman]

All 1uz ecu's can be wired fine in conversions.

Did a diagnostic port get wired in? I would normally connect a scan tool and have a look at what the ECU is seeing.

Is your IAC plumbed in correctly? If they arent they will cause AFM codes.

 

[fourstars]

The only diagnostic port install is located inside the engine bay! I do have grouds bolte up on the passenger wall. IAC, havent check that yet! but that would have gotten a DTC rite?

 

[fourstars]

Okay, check the IAC and yes it is connected correctly. I unplug the main hose that goes to the intake arm and I can hear and feel it sucking air. when I plug it up with my thumb it shuts off engine. So I know its working.

 

[gloverman]

Have you checked the voltage the ECU is seeing for the TPS?

Factory there is a second diagnostic plug under the dash which needs to be wired in to give accurate live data from the ECu using a scantool

I have diagnosed many 1uz which are throwing strange (sometimes unlisted codes) about 75% have been wiring issues. Other 25% have been the ECU at fault.

Do you have both the secondard oxygen sensors connected?

 

[fourstars]

No i have not check voltage at the ECU for TPS. I have 4 O2 sensor and are connected. however i am recieving a DTC for the right sub O2. I didnt think that may be an issue related to AFM or TPS. i was planning to get that resolve last. But enable for you to help i could get that fix!

 

[gloverman]

Both the AFM and the TPS use the 5 volt rail from the ECU as does the sub TPS. I would expect a sub tps code as well. I would check the 5 volt supply to the TPS and the AFM. Unpluging the AFM should throw a code 22- air temp sensor. I have replaced and rebuilt a heap of ECUs with a blown 5 volt but test properly first

 

[fourstars]

5volts are found on all three plugs , sub tps, main tps and afm. tested the ground too, on all the plugs too and everything good.

 

[fourstars]

Some additional info if it may help:

I’ve looked at some of the wiring diagrams for these sensors and found 3 different diagrams. All look similar. I’ve wired my system matching all 3 and still same DTC. Im not sure as to how fast the ECU finds a DTC. But after resetting the ECU and restarting the motor I get a DTC light right away. Motor didn’t have to be warm up or anything.

There is no coolant in the motor, no transmission oil, and no transfer case gear oil (4x4), if it matters. Found VSV EVAP sensor vacuum line was rip and electrical wires slightly damage by the plug. It is now fixed. Not sure how that can contribute. There is a vacuum line in the rear of the manifold by the firewall that is plugged up. It once was plug into a VSV on the heater control valve from the donor.

As for wiring up the motor, I DID NOT dissect the harness like most would. On the ECU side of the harness I kept all the female / male plugs from the donor and attached those to the body harness of the truck. Also de-pin TRAC control wires.

On the other end, you have 3 plugs from the engine wire harness, I wired up 4 relays there (Fuel, Starter, EFI, and Main).

 

[gloverman]

I was thinkiing about this one and remembered the early ECU's dont throw a DTC for the secondard TPS. Ive been doing too many gen 2 motors lately which do unless the ECU has been setup for non trac.

You should never run a trans without oil. Also running the engine without coolant for some time can cause the waterpump seal to overheat and fail.

Some DTC will be set simply by turning the key on depending on the conditions needed to set them.

Have you checked your 5 volt rail?

 

[fourstars]

5 volts rail? Im sorry, I'm confuse! i assume 5 volts from the plugs.

 

[fourstars]

where can i check for the 5v rail?

 

[gloverman]

yes 5 volt to the plugs. This is the regulated 5 volt from the ECU. As long as it is present.

What voltage are you getting back from the TPS? VTA1
Also check the idle switch. IDL1. It supplies an earth back to the ECU.

Afm supplies a fequency so hard to measure without correct gear. I use the scan tool for this.

 

[fourstars]

VTA1 @ 1.74v (Black probe on - on battery and red probe in plug VTA1 ( pin 3 / yellow wire on main TPS )

IDL1 @ 0 ( no ground ) red probe on + on battery & black probe in plug of IDL1 ( pin 2 / red wire on main TPS )

Recheck the 5v and it is present on all 3 plugs.

 

[fourstars]

I think I've found out the problem. Not sure. Anyhow, after testing these pins, I tested the Blue & Red wire which contains the 5V from the ECU again and found out that when I test the continuity of that wire, it had a LONG beeped all the way to the ECU. When I test the continuity with the other Blue & Red wire on the other plugs it tested out good. When I tested it with the Brown (Ground) wires, it BEEPED only ONCE. I then tested continuity from all the BLUE & RED wire from the ECU to the 3 plugs with any GROUND including the frame and motor, I get just ONE beeped. I even tested it with the battery negative and positive cables, and I continue to get ONE beep. I'm in the process of taking off all the grounds and hoping to find a short somewhere.

 

[fourstars]

checked everything and splice the harness and i think it maybe normal! i even check the pin on the ecu for continuity and it beep. so time wasted, can someone confirm if this normal operations?

 

[fourstars]

help! i'll will pay for any consultation services!

 

[fourstars]

redid the wiring and did not find a problem. same problem, afm, tps, and rear right o2. so i switch the o2 sensor to the left side and same code appear for the right side. reset every thing and found out check engine light appear rite away again. feels like no signal that the sensor exist!