Yes, brown is ground and s/b tied into other grounds there by the manifold. The E2 position of the ECU should also be tied to that same location. Tim
Yes, brown is ground and s/b tied into other grounds there by the manifold. The E2 position of the ECU should also be tied to that same location. Tim
Pooh, was thinking that was the problem, brwn should not be grnd... odd that my skematic does not show it grounded....
oh well, stumped..... cause i know the wires are good to thw and e2, i swapped out maf and the other cold start temp sensor from my spare engine....
any idea what else could keep the code 4 persistent, i mean right away, too... tells me a short or something bad.... i have not double checked engine ground but ran a wire to manifold ground from battery...
clue, when idling, and then open throttle it immediately dies if i don't take the cts out..of circuit...
had throttle body off, all clean...as is tps... if i was getting stray voltage to ground lots of dashlifghts would be going bonkers...
been pondering over this for months and months...... i mean when the switch is flicked, taking sensor in and out, , it dies quick, not like going too rich or lean which would sputter it out.
I have every wire out of the harness to the ecu, doing a total rewire...
i was going to get to the idle air valve underneath manfld but hoping i would not need to go that far... and seems pointless with the trouble code persistent, a leaky intake would not give temp code...
oh well, been desperate before, and know it will be solved one day... you have a great forum, all those other ones are so gamed for marketing, probably facebook behind them.
one other thought, that has been a huge problem over many years is that friggin alternator and booby trpped location throwing off voltage due to drippy p/s fluid, been there and done that... but it may be cracked insulator or some lil something...
maybe if i just stuck a 2000 ohm resistor btwn e2 and thw, then add a lil rheostat that i change manually.....
Sorry for stating the obvious, but did you actually test the thermistor values? These things can be bad right out of the box.........especially if aftermarket.
yep, check, but so determined, bought another one...tested good too....
stickin me a fail safe resistor in there tomorrow, see what happens after clearing code....
Pull the sensor connector off and verify resistance between the two conductors. Once you know what it is (let's say 2000 ohms), put the connector back on then pull the ECU harness and check between E2 & THW positions. You should read the same value as you did on the sensor. The sensor is basically just a resistor and the ECU is an ohm meter. If the sensor is good, and it's resistance can be accurately read from the ECU harness, then there should be no code (assuming it's been cleared after the remedy). If the ECU is calling foul, when in fact there is none, then the ECU itself could be the problem.
If you can't read correct resistance from the ECU harness, then the circuit (wires) are the problem. The biggest suspect would be the connector. Check that thermistor connector with x-ray vision. Make sure the little conductors inside are not deformed and verify the wires aren't chaffed through or broken inside near the connector. Tim
alright Perry Mason is going to get to the bottom of this tomorrow.... and report back.... thnk you ... i had every engine part disassemebled and in boxes for 5 years back in the 90's bfore i got my baby put back together and this and my 72 mercedes 240d are my lil darlins.... not so much my neighbors though...
Glory bee! got the code 4 light off.... Just went ahead and installed the new connector at sensor and that did it.... must have been an intermittent somewhere that would short when plugged in...
Now on to final tuning up and getting it all in top shape... thanks for the moral support and repeating the obvious on what needs to be done....
Napa had the connectors for $8 the tps was around $16
their echelon line pn 2-18457 and ec173 for tps
That's awesome! Happy to be able to help. You did the real work though. After 28 years in the intense heat these connectors can certainly become problem areas. Tim
I am also getting codes 4 and 11.
In cool weather, when my engine is cold, the van runs like total crap. Idles around 500 and the engine shakes, but it does not stall. Once the engine warms up the van runs well.
When timing is set properly the van runs like a very old dog. I have to manually advance the timing to 20 something to get any power out of it.
Checked my water temperature sensor. It tests fine. Have not gotten around to checking my TPS (given its unknown age perhaps I should just replace it). However, today I noticed that I can see the gasket between the throttle body and intake is actually visible! Could this be what is causing my cold engine idle problem?
After a very long ordeal, I SOLVED mine. the intake plenum gasket, the one between the top and bottom of the entire manifold., was leaking. When engine heats up, stops leaking. I did the senor thing, the tps, and much much more until I tore the ole gal down, and saw some gasket missing.... and then it made sense, once while troubleshooting and fiddlin with stuff, running really bad, i had a misfire and saw a puff of smoke come from the area, and i thought, wtf..... should have paid more attention and got right to it., but skipped over it to my ignorance....
just a thought...I would not be surprised if this is others problem, too.... mine came on real, real slow, hard starting at times...but could get it running by pulling of temp sensors, which was just tricking the ecu..... I rebuilt my 83 , 100% and this is the 1st issue since i did the job, back in 1999...
Last edited by TinyBird; 08-20-2012 at 11:01 PM.
TinyBird -- Did Napa Echelon pn 2-18457 fit on your coolant temp sensor? It is described as having a "centered index slot". My CTS has a index slot that is off-center. Did you just push the connector on over the off-set slot?
idle-up temp switch and cold start timing switch is bad. Same problem i just fixed in my van. i had codes 4 and 11.~ My MAS and my TPS gave bad numbers and had to be replaced as well, replacement of TPS got rid of code 11 but did not fix problem:
At the sirens of humanity we STOMP!
Thanks for that tip, Rawb. Looks like you are right. My idle-up temp switch is not checking out - there is resistance (1.15 K ohms) between the terminal and body when oil temp is cold (less than 103 f). Resistance of my cold start timing switch (54 ohms @ 20 deg C) is almost within service manual specs (38 - 44 ohms below 30 deg C). Water temp sensor and cold start injector appear to be OK.Originally Posted by RawbSpear
I searched online for an idle-up temp switch but haven't found one. Do you happen to have a part number or online source for that switch?
Forgive a basic question, but what/where is the MAS or MAFS?
the mas is under the drivers seat. It is attached to the top of the airbox where the filter is.
code 4 is a bad temperature switch. I i were you i would replace all three sensors/ switches on that tree..
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Last edited by RawbSpear; 09-11-2012 at 02:59 PM. Reason: more detail
At the sirens of humanity we STOMP!
I have seen some vans without a idle-up temp switch. Instead they only have a bolt in that hole on the radiator cap column. Is the idle-up temp switch only on vans with A/C? My van used to have A/C but it was taken out before I got the van. My idle-up temp switch does not have the black cylindrical connector. Instead it has a small spade connector.
I'm going to clear a couple things up here. The switch Rawb is referring to as the "Idle-up Temperature Switch" is actually the "Water Temperature Switch". These were only installed on vans with factory AC and don't have much to do with the way the van runs. Toyota put these switches there to combat the "Heat Soak" issue that can affect these vans (particularly the ones that might be running AC in hot climates). If you're having trouble with heat soak, then I would recommend pulling the wire from this sensor and permanently attaching it to a ground point (new switches of the correct value are NLA). The result of grounding this wire will be slightly higher fuel pressures for a couple of minutes each time you start the van. This higher pressure will reduce potential runability issues caused by heat soak.
For more information on this subject read THIS THREAD & review the PDF attached to my 1st post. Tim
Tim you are wrong.. I know what i am talking about, i just replaced all of them and had to find out what they are called and what they did so that I could get my car to wrok properly.
The idle up temperature switch I got from TOYOTA!!
Go look in your manual in the FI section DUDE!!!
PS my car works perfectly. thank you
At the sirens of humanity we STOMP!
Toyota routinely uses different names for some of these components so you could be correct about them using the term "Idle-up", but the function is as I described (check the service bulletin I linked to). The other component you refer to as "Temperature Switch" with the Airtex / Wells reference is actually a sensor (not a switch). It's possible Toyota may have referred to this component with a different name........somewhere, but as far as function it is not a switch. It is a thermister and it changes resistance based on temperature (no switching action going on). The ECU monitors this one and adjusts fuel mix based on the resistance it sees. This particular sensor is VERY important in regards to driveability issues. If this one is bad the van will run like total crap. The part labeled M.A.S. is actually the AFM (Air Flow Meter).
For the most current tech information on the "Water Temperature Switch" please check the service bulletin I linked to as Toyota published this AFTER the service manuals were printed. Tim
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