BII EEC IV code 15 question HELP

[dispatchrobb]

I have 89 BII with rebuilt 2.9 engine, 5 spd manual. Got it back from shop and check engine light was on. They said they couldn't get the codes on their tester to come up. So I warmed it up and hooked up my code scanner, and got code 15.

Vehicle runs like it's missing, or rough. Check engine light goes on and off while driving. Timing is good, firing at all cylinders. I know it's warm cause manual temp gauge reads 190, and vacuum is good, have gauge hooked up and reads normal for vacuum tests.

Cleared and rechecked codes. Shows code 51, the coolant temp high voltage, and 15.

I checked the pins 1 for 12v, and reads 17.68V. Battery reads 17.68V. Pins 40 and 60 are good grounds.

Is my EEC Toast, and would the 17V be too high for the EEC?

 

[adsm08]

17.6V is too high for a 12V battery. I don't think your computer is damaged, but it assumes all of it's reading off a supply voltage between 12 and 14V, so if the sensor is getting 17.6 or more then the signals coming back will be higher than expected and codes will be set.

I would look at the voltage regulator on the alternator.

 

[kimcrwbr1]

It could be a short in the alternator wire going to the ignition switch causing the alternator to run wild or a bad regulator. Fix the obvious first the charging voltage should be no higher than 2.5 volts over battery voltage. Fully charge the battery disconnected from the truck and measure the voltage and let sit overnight. If the voltage drops any the battery needs replaced before you can test the charging system. The tech library has a section on charging system diagnostics, read it through a couple times and then go through the wiring good.

 

[dispatchrobb]

Update. Found the TPS plug was not plugged in. So that cleared up the check engine light. Engine is still acting funny, like missing, idling up and down, and just not right. Tested the TPS, and got 7.6V on the pwr, and 1.40V up to 7.68V on the Signal. Smooth increase, so TPS shouldn't be bad, but will these values make it run horrible, since like you said, higher values will make the computer act up?

Thanks

 

[dispatchrobb]

Update number two. Did a little more playing around. Battery today, engine not running, was 18.8V. Running was 22.5V. I changed out the voltage regulator, and no change, still 22.5V at the battery when engine running. No CEL of any kind. It's drivable, but runs horrible. I am at a loss.

 

[kunar]

is your multimeter on the fritz? borrow one from a friend or neighbor...

 

[dispatchrobb]

Based on these readings, I hope it is the multimeter. I have access to an analog one, I'll try it tomorrow. The Voltage gauge on the dash does read normal.

Even if it comes back normal, it still doesn't clear up the shuddering when it's running. If the TPS was unplugged when the shop timed it, would that mess up setting the timing enough to make it shudder when it's running?

I'm just trying to figure out why it doesn't run smooth.

 

[dispatchrobb]

Yep, multimeter was on the fritz. All readings were normal, and exactly where they needed to be on the batt, alt, and TPS. No codes, everything comes back good. Timing is dead on 10 BTDC. Still runs like it's missing, so gonna check out the plugs, since all six wires give off spark using the spark tester. If that's not it, I'm gonna throw a rock at it, cause that's all I can think as to why its running bad.