Hacking the EFI computer

[Cynxing]

May 86/87 Toyota Dolphin 21' 22RE EFI

Hi All,

Now that I'm in one (dusty out in the middle of nowhere) place for a while, I can attend to the nagging issues that have attended this journey.  The check engine light, quiet up until Tucson, is now flashing in bezerk spasmodic patterns.  It is time to hack the computer and get a good reading - NOT while I'm try to drive in high wind conditions. 

Linda, you mentioned this article http://www.4crawler.com/4x4/CheapTricks/TroubleCodes/

I did find that, and I have the two little diagnostic yellow plastic cylinders on the sidewall, but it does not say where you stick the ends of the hair pin.  Just randomly one into one side and one into the other?  I am hesitant to stick metal into live electric areas with which I am unfamiliar.

So here are my little yellow doohickeys.  They have specific plug patterns each.  Where should I poke 'em?

[WME]

So what are you don't like pretty blue sparks? Its the smaller one, it should only have 2 wires in it.

There should be a rubber grommet type holder on the fender. Keeping the plugs there will keep things cleaner.

[Maineah]

OK that's a 86 truck one yellow connector only has two wires that's the two you jumper.

 

[Cynxing]

Ok I'll try that this afternoon.  And they do live in the rubber holder thingies when not posing for photographs.  So what's the big yellow doohickey for?

[Maineah]

1 hour ago, Cynxing said:

Ok I'll try that this afternoon.  And they do live in the rubber holder thingies when not posing for photographs.  So what's the big yellow doohickey for?

I don't know. If I remember it has little plastic plugs inside that kind of block the terminals maybe factory diagnostics.  

[Cynxing]

So -   Sane, slow, repetitive flashes that a person can actually count.  4 and 5.

4 - Open or shorted Water Thermo Sensor
(THW) circuit
Defective THW
Defective ECU

5 - Open or shorted Oxygen Sensor circuit
lean or rich indication (with injectors full rich or full lean)
Defective 02 sensor
defective ECU

So I have no idea where the Water Thermo Sensor lives. When the radiator was done they replaced the thermostat sensor.  Is that the same thing?  If so, that was put on a mere month ago. 

I put the new O2 sensor in only two months ago.

What to do?

[Maineah]

Replace the water temp sensor that probably is causing the O2 sensor to read rich. Drawing a complete blank I can't remember where it is! kind of think it's on the thermostat housing. There are two, one is strictly for the gauge it has a single wire the other is for the fuel injection it will have a large waterproof connector.

[linda s]

[linda s]

For some reason I couldn't write anything and still post the picture. The water thermo sensor not working can cause most of  the problems you've been having. Certainly worth a try

Linda S

[WME]

AND so?

[Cynxing]

Had to order the sensor.  Put it in this afternoon with a storm about to start - DRAMA!  Just checked the codes and WHOOP WHOOP a staid, calm little single flash.  Nothing going on here.  Nothing to see here.  Move along. 

But my battery is making clicking hissing noises like a soda bottle with the cap partly unscrewed.  Two months ago I cleaned the corrosion off the positive terminal and put vaseline on it.  It's already corroded again.  Time for a new battery?

[WME]

Emergency volt meter check. What your describing is called "boiling battery".

Causes a bad alternator... a battery with shorted cell(s)

 

[Maineah]

Hot to the touch batteries are not a good thing. Check the voltage if it's above 14 volts at idle it's time for a new alt. the regulator is inside cheaper to buy one then to fix it.

[Cynxing]

It's pouring rain and dark right now but I'll test voltage at first opportunity.  I can't imagine it was boiling when I heard the sputter crackle because I had just turned on the vehicle very briefly.  Unless batteries can get hot in the space of a minute or two?  And judging from the terminal crud I cleaned up when I bought this in October, has the bad battery been causing some of my grief for months?  Obviously not stuff like the radiator and TPS, but the non starting at Quartzsite and...? 

New battery coming up.  I'm sufficiently rattled by the noise I heard today.  How long do you think a nice Interstate would last?

[Maineah]

It would be a real good ideal to check the voltage before you replace the battery it's best to overcharge a battery that's going to be replaced than a brand new one.

[Cynxing]

Ok, so I blew that one.  I was so excited to find a battery in this little town that actually would work that I changed it out in the rain without checking the old one first.  And I don't know what you mean by "overcharge a battery that's going to be replaced" - Is the alternator going to now do something evil to the new battery?????  I gave the old battery to the NAPA place.  Is it checkable off the vehicle?

[Cynxing]

Unclear on the concept.  The new one reads 12.16 with the headlights on.

[linda s]

What he means is if the regulator in your alternator has failed and it's pumping out too much juice your going to trash the new battery too. Check it again with the lights off

Linda S

[Derek up North]

Engine off, fully charged should be ~12.6v. Engine running, everything off I'd want to see ~14.5v. Engine running, with 'high load' (Hi-beams, heater fan and wipers on hi) you should still see 14v+ to show the alternator can keep up with the load.

[WME]

14 minutes ago, Derek up North said:

Engine off, fully charged should be ~12.6v. Engine running, everything off I'd want to see ~14.5v. Engine running, with 'high load' (Hi-beams, heater fan and wipers on hi) you should still see 14v+ to show the alternator can keep up with the load.

x2

You should be able to check the battery out of the truck, you just can't check the charging system,

Edited February 15, 2018 by WME

[Cynxing]

30 minutes ago, Derek up North said:

Engine off, fully charged should be ~12.6v. Engine running, everything off I'd want to see ~14.5v. Engine running, with 'high load' (Hi-beams, heater fan and wipers on hi) you should still see 14v+ to show the alternator can keep up with the load.

Engine off, fully charged: 12.75
Engine running everything off: 14.58
Engine running, hi beams heater fan on:  14.49
After shutting off: 12.86

[DanAatTheCape]

34 minutes ago, WME said:

x2

You should be able to check the battery out of the truck, you just can't check the charging system,

minor point, but alternators and generators can be bench checked....    most any auto parts store has a testing machine. Usually they can test on the vehicle too.   Off the vehicle, then the alternator or generator is mounted on the machine, with the correct wiring harness used - then they spin it up and test.

[Totem]

17 minutes ago, DanAatTheCape said:

minor point, but alternators and generators can be bench checked....    most any auto parts store has a testing machine. Usually they can test on the vehicle too.   Off the vehicle, then the alternator or generator is mounted on the machine, with the correct wiring harness used - then they spin it up and test.

I love those things - AutoZone uses one that will always 100% of the time say "FAILED" if the "outside vendor" is option toggled and the "AutoZone part" is not toggled. That's for the people that come in with another brand. if the autozone brand option toggle is on it will test "PASS" on all the test even if its fried. Best Duralast lifetime warranty ever; lol

Edited February 15, 2018 by Totem

[Maineah]

4 hours ago, Cynxing said:

Ok, so I blew that one.  I was so excited to find a battery in this little town that actually would work that I changed it out in the rain without checking the old one first.  And I don't know what you mean by "overcharge a battery that's going to be replaced" - Is the alternator going to now do something evil to the new battery?????  I gave the old battery to the NAPA place.  Is it checkable off the vehicle?

Yes it can if you find a lot of recurring corrosion there is a real good chance the battery is being overcharged  by themselves they can not do that 14.6 is a good bit on the high side for no load and it probably goes higher with engine revs. Next question have you had problem starting the MH before you replaced the battery? You can take it off and have it checked or you can do it the easy way on the vehicle and use a voltmeter and that seems like that is what you have done. The voltage regulator is inside of your alternator it can indead cause an over charge situation if you fancy your new battery it needs to be checked out. normal voltage is between 13.2 to 14.2 depending on load any thing above 14.2 is on the high side and it should be checked with revs a good bit above an idle. I have seen 12 volt alternators make 32 volts with max unregulated field voltage.

[Cynxing]

Yes it failed to start after sitting for five days once back in Quartzsite.

I was planning to drive two hours to Albuquerque Saturday.  Easier to find a mechanic there as well.  I just looked at the video for swapping out the alternator and was completely intimidated.  Any way I can test the voltage regulator without pulling the alternator?  Will I damage the new battery with a two hour drive?

Edited February 16, 2018 by Cynxing
Wrong words

[WME]

13.9-14.7 vdc are the acceptable limits for an auto charging. You look good

 

[Maineah]

Progresive Dynamics 45 amp charger 

Specifications

• Input: 105-130 VAC, 725 Watts
• Output: 13.6 VDC, 45 Amps
• Dimensions: 8.25” x 7.25” x 4.7”
• Weight: 4.5 lbs.
•  
• www.lifewire.com/understanding-alternator-output-ratings-534785

No load voltage at idle of 14.6 volts is excessive.

[Derek up North]

http://www.aa1car.com/library/charging_checks.htm

[WME]

!4.7v at idle is a bit much, 14.7v at 3000rpm is upper long term limit of safe. OP posted 14.58v as max v.

Cynxing please try volt check way above idle (3000rpm).

Bases on your reports I would say you had a toasted battery. What happens with a battery with a shorted dead cell is that instead of 14v+ charging 6 cells its charging 5 cells and the v per cell goes way high and will boil the battery. With 1 short cell you could probably have normal starting MOST of the time, but with the slightest thing off no start. With 2 shorted cells and you have a very very marginal start v, like only start under absolutely perfect conditions and almost instant boil on the remaining cells.

FWIW I think your good to go.

Edited February 16, 2018 by WME

[Maineah]

My point, there is not earthly reason it should be that high particularly with a brand new battery and no load. I would be surprised to see much over 13.2 under those circumstances.

[DanAatTheCape]

23 hours ago, Totem said:

I love those things - AutoZone uses one that will always 100% of the time say "FAILED" if the "outside vendor" is option toggled and the "AutoZone part" is not toggled. That's for the people that come in with another brand. if the autozone brand option toggle is on it will test "PASS" on all the test even if its fried. Best Duralast lifetime warranty ever; lol

that is quite an accusation there...

[Cynxing]

So glad I have rustled up some friendly contrasting information. 

I will rev it up before leaving tomorrow to see what it reads.  If the sleet is still coming down, that will pre-empt my trip anyway.  I called the NAPA mechanic shop guy who sold me the battery and he agreed with WME that 14.6 was ok. I will keep an eye on it and take care not to roast the new battery - which by the way is larger than the other one... not sure if that is of any importance.

Thank you all for your input.  The hive mind is powerful.

[Derek up North]

Larger size generally equates to more CCA (Cold Cranking Amps). Might be useful in Montpelier in Winter!

 

[Cynxing]

Oui!

Ok, I had a friend read off the volt meter while I revved (no tachometer, sadly) and had brights, wipers, and heater blower on.  He said it was 14.53. 

From Derek's link I found this nugget:  "The lower the temperature the higher the charging voltage."  It snowed this morning and it is 36 degrees right now. 

I'm a'goin'

And as a parting thought.  Is a "Tacometer" a device to measure how spicy your salsa is?

Cheers, C

[WME]

If your heading to VT you won't have to worry about a tacometer as the chili is an unknown fruit.  Salsa is only to be found at the exotic foods section of SS Pierce in Boston.