1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

[evilunclegrimace]

Perform a voltage drop test on all of your cables

 

[JW454NOVA]

If the sensor has appropriate resistance with temperature, and the computer thinks it's -40, you clearly have a wiring problem between sensor and ECM.

It'd be worth checking the TPS as well. Either the TPS is toast, or the wiring is, since the voltage doesn't change as you open the throttle.

Given that the battery voltage is in the toilet via the scan tool, it seems like the wire harness may be a three-way fail; and who knows what the other sensors are showing.

Battery charging at 13.6 seems low. I'd have expected 14.2 or perhaps a bit higher. What is the battery voltage with the engine off and no load? Is the battery so depleted that it's sabotaging the rest of the electrical system?

Are there any other grounds that I'm missing? I've replaced the head to frame ground. Replaced thermostat ground eyelet and cleaned mounting surface. I have the entire wiring harness exposed and don't see any issues with any wires. Wondering if I got a defective new ECM.

 

[scott2093]

Maybe could back probe the ecm at power and ground to make sure you get what your battery is saying...

 

[JW454NOVA]

Perform a voltage drop test on all of your cables

I will try that. Thanks.

 

[JW454NOVA]

Maybe could back probe the ecm at power and ground to make sure you get what your battery is saying...

All powers and grounds are good at ECM back probing. Is it possible I installed the wrong PROM? It was a JET prom. Here are pics of scan data KOEO. Battery voltage shows 0.00. I also noticed that the prom ID number keeps randomly changing without touching anything.

 

[JW454NOVA]

More pics of codes and data.

 

[scott2093]

yeesh...wild...
Maybe you're on to something regarding the prom. I'm always hearing that getting things working stock is the best avenue. I'm guessing the scanner checks out on other vehicles...

I noticed in the manuals section that the 88 vintage may have wiring diagrams that could be useful but I'm not familiar with this series.. But there is the manual with p series if that's what this is and it has some tbi diagrams in it...nothing in the 89 afaik...

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[JW454NOVA]

yeesh...wild...
Maybe you're on to something regarding the prom. I'm always hearing that getting things working stock is the best avenue. I'm guessing the scanner checks out on other vehicles...

I noticed in the manuals section that the 88 vintage may have wiring diagrams that could be useful but I'm not familiar with this series.. But there is the manual with p series if that's what this is and it has some tbi diagrams in it...nothing in the 89 afaik...

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

THANKS good buddy

 

[evilunclegrimace]

Post your ECM P/N and PROM ID please. I might have a ECM and Prom on the shelf. I will check when I get back to the shop.

 

[JW454NOVA]

Post your ECM P/N and PROM ID please. I might have a ECM and Prom on the shelf. I will check when I get back to the shop.

1228747 ECM and "AKWA" PROM chip. I replaced with the Cardone 77-8747 and put in Jet chip #289128. Is this the wrong Chip? The capability chart shows 89-90 Chev and GMC truck 5.7. Any possibility this van needs a different chip? Any thoughts? I attached the chart below.

On a side note, I removed the mt2500 snap on brick out of the equation and started relying on flash codes. Jumped the obd1 and I'm getting only the 12 flashed several times. It's showing no codes at this time. I'm even more confused .