check engine light no codes

[gushaman]

Did a search but maybe im using the wrong terms?
was gettimg an intermittant hesitation and check engine illumination.
checked the codes and replaced tps and wiring to sensors on water neck, especially the wiring to coolant temp sensor for ecu.
am still getting check engine intermittant illumination, but no code is being set or stored!
Any ideas?

[timsrv]

It could be a harness issue, but it's more likely your ECU is failing. If you have an extra one sitting around put that in to see if the problem goes away. If you don't have an extra one, considering the age of these vans, I would recommend getting one. You can usually find these on eBay for ~$50. I now keep at least one spare around for each of my vans. If nothing else they can be good troubleshooting tools (saves time for when problems like this pop up). Tim

PS: When purchasing used, to be sure it's compatible, replace with the same Toyota part number as the one you're taking out (number plainly listed on front). Tim

[robgagnon]

I had intermittant cut-out with illuminated check engine light just for the brief second it was cutting. Wiring schematic shows that both power and ground to ECU also route to 3-conductor test connector by aircleaner. I ran an extension from this connector to an analog meter sitting in passenger seat and drove around. Power nor ground were disrupted so that showed that relay, harness, connectors seemed ok. Turned out to be ECU. Have not opened bad unit yet, but probably broken traces on circuit board which might be fixable with a resolder, but as Tim says, extra ECU was handy. Some ECUs appear to be interchangeable: I think these two are interchangable:

4YE ECU 89661-28040 86 87
4YE ECU 89661-28060 86 87

[robgagnon]

I mean:

4YE ECU 89661-28040 (used in 1986 1987)
4YE ECU 89661-28060 (used in 1986 1987)

[gushaman]

I am planning on checking the ecu ground but alas I do not use ebay anymore, its a long story

[gushaman]

I had intermittant cut-out with illuminated check engine light just for the brief second it was cutting. Wiring schematic shows that both power and ground to ECU also route to 3-conductor test connector by aircleaner. I ran an extension from this connector to an analog meter sitting in passenger seat and drove around. Power nor ground were disrupted so that showed that relay, harness, connectors seemed ok. Turned out to be ECU. Have not opened bad unit yet, but probably broken traces on circuit board which might be fixable with a resolder, but as Tim says, extra ECU was handy. Some ECUs appear to be interchangeable: I think these two are interchangable:

4YE ECU 89661-28040 86 87
4YE ECU 89661-28060 86 87

so it turned out to be a bad ECU? i have found that when mine hesitates/cuts out, theres a half second where the engine tries to die before the "limp mode" or whatever takes over from the ecu/sensors. but if I slap the outside of the sheetmetal behind driver door when it does this, it will make the light go off and it will run normal? according to repair manual there is not a ground in this location, looks like the nearest ground is the ignitor??? is this true? is there supposed to be a gnd @ ECU?

if i can find a similar plug i would like to make a 3 connector test light extension. i love how in the repair manual it says check this check that.....try another ECU.....thanks toyota, if i had another ECU I wouldnt be looking at this part of the manual....

[gushaman]

Ignitor and shielded wire are grounded fine. Started engine, check engine light was on. Slapped outside of ecu area and light went off. Also wiggled the wire bundle at front of air box and got a split second hesitation but no light. Havent taken seatbelt out yet to look at ecu, but do yall think a bad ecu would respond to being slapped??? Possibility of break in wire bundle exists, or loose connector at ecu but i doubt it. This is my daily driver until i put new steering rack in my 2wd, so thats why i havent inspected ecu yet

[timsrv]

I know I'm weird, but for anybody using an older vehicle like this for a daily driver, I find it hard to imagine not having an extra "everything" laying around. Anymore when something acts up I just start swapping parts with known good ones. I know it's not the most intellectual way to diagnose, but it's pretty darn fast and reliable . Tim

[gushaman]

used to have extra everything, in the five years i was vanless, i got rid of a few pickup beds full of van parts DOH! And since I am just now looking to buy a house, it is gonna be a while before I can acquire any more extra parts. My parents are already dismayed about the 16 wheels and tires, plus I have about 3/4 of another 4wd van in a storage unit (minus the body), but no ecu :(

[gushaman]

Update: removed ecu, and just layed it on hump. No cel illuminated for a day. When it came back on, my wonderful girlfriend helped me figure out which wire is to blame: its the black/red tracer wire, it is a little loose inside the connector or a short further away. I am looking at the pdf manual, but it doesnt show that wire from ecu, what is this wire!

[timsrv]

Black wire w/red stripe goes to the STA side of your cold start injector time switch. What code is being displayed?

[gushaman]

Still no code, the light goes off when blk-red wire is wiggled.

[gushaman]

What is STA? seems like the wire is loose in the plug connector

[timsrv]

STA is the 3 letter code they assign a pin of the cold start injector time switch. It probably stands for something, but don't know off the top of my head what it is. Did you ever swap ECU's? Sure sounds like you got a flaky one............perhaps a loose solder joint inside the case? Tim

[gushaman]

STA is the 3 letter code they assign a pin of the cold start injector time switch. It probably stands for something, but don't know off the top of my head what it is. Did you ever swap ECU's? Sure sounds like you got a flaky one............perhaps a loose solder joint inside the case? Tim

thats possible, but with the way its wiggling I am leaning towards loosness in the connector itself.
I would like to try another ecu but i dont have one. its the one that was mentioned earlier in this thread that ends with -----60

[gushaman]

i see, the manual has the STA listed as a black wire. maybe that pin has come loose like you said, Tim.....used ecus are from $80-$150 online, maybe i can find one a lil cheaper, lol im a skinflint, thats how i got into these vans in the first place!

[bushcat]

So, bought this new van and going through all the issues. Just replaced the alternator. Also, fixing the squealing power steering pump by cleaning the filter.

Anyways, I was told that the PO to the PO hooked the battery terminals up the wrong way and fried the ECU. He replaced the ECU but it’s always had a check engine code lit up. It didn’t reset when I changed the alternator, battery terminal was disconnected for more than 30 seconds. Check engine light did not go off when reattached. I tried reading the codes but no blinking is happening. Could it be a bad ECU?

Found this post too: https://www.toyotavantech.com/forum/...will-not-reset

Thinking it could be the ECU. Does the van need to be warmed up to read the codes? (it says typical operating temperature, not sure if that means the need to warm it up).

[timsrv]

Perhaps the PO to the PO put the wrong ECU in the van? If you give me the VIN I may be able to narrow down the correct part number? Any other info would also help (year, trim level, transmission type, etc.). Tim

[bushcat]

So, I checked the ECU part number and it matched with the ECU diagnostic post that’s on here.

89561-28010

1984 Toyota LE 5 speed , 3y
JT3YR26V2E5014052

Just bought a replacement (89561-28010) on eBay for $45. even if it's not the ECU, from what I read on here, it's good to have.

[timsrv]

Being an 84 makes it easy (as there's only one from 84 - 85). And yes, you got the right one. Have you swapped it out yet to see what happens?