4l80e/6.5 NA limp mode??

[Roberttx13]

2

 

[Roberttx13]

2

 

[WarWagon]

You have an ECM. It only controls the transmission and other than bulb check will never turn on the SES light. No emmisions problems = no SES light. The paper clip is correct and should flash 12.

It's not. ECM is not happy. Vans may vary, but, start by looking for the ground on the passinger side head rear. Should be 3 small wires. Take it apart and clean it.

Check supply voltage next. You will need a diagram IMO 1993 pickup should be same.

Next diagnose ALDL conector voltage with chart. IMO you can have something shorted messing the ECM up. Note no 12v supplied at ALDL. This said I would trace the TPS wires back looking for damage. Also check the RPM sensor wires - like a distributor back top of engine.

The trans conector full of oil is bad. Electrical cleaner. Final fix later. Oil is an insulator on connections. Also check speed sendor wires as the insulation falls off at plug and where they join main harness. Speed sensors on transmission. May be two, input and output speed.

 

[FellowTraveler]

That setup may very well have a speed sensor at the oil pump drive instead of a TPS on the IP.

 

[Roberttx13]

Okay so the ground has been sanded and put back together tightly and what do you mean by no emissions no ses light?
I traced the aldl and so far nothing broken or chaffed that I've seen...I did find bad wires at the bulkhead connectors that I'll post a photo of but I'm not sure what they go to I'm reparing them now and putting more electrical greese.

And I'm not exactly sure where the rpm sensor is located I see a small round black object with 2 wires coming off at the rear of the engine. I've cleaned off the trans plug and blew all the atf out so that should be okay for now all the wires on the plug look fine

I've replaced the input speed sensor not the output so far but I'm going to check the wires that go to those plugs right now.. so do you have any idea where I can find my ecm to make sure all the wires in and out are okay. I don't see it under the dash and no glove box in this truck just the AC blower down there.

 

[Roberttx13]

That setup may very well have a speed sensor at the oil pump drive instead of a TPS on the IP.

Where would that oil pump be located on the engine?

 

[EWC]

You have a G van , not a truck . That is a TCM , only runs the 4L80E . DB2 pump , throttle cable is an obvious clue . The SES light should come and then go out if you have no codes . The jumper wire in the ALDL should give you codes or a code 12 . The cavity down and to the far left might be for the ABS codes . Those were checked by using a jumper from the top right to that cavity . As mentioned by WW , any oil in the trans connector is bad . Try cleaning it out and reconnect .

 

[EWC]

The RPM sensor is right at the back of the engine with the fuel line running over it .

 

[Roberttx13]

You have a G van , not a truck . That is a TCM , only runs the 4L80E . DB2 pump , throttle cable is an obvious clue . The SES light should come and then go out if you have no codes . The jumper wire in the ALDL should give you codes or a code 12 . The cavity down and to the far left might be for the ABS codes . Those were checked by using a jumper from the top right to that cavity . As mentioned by WW , any oil in the trans connector is bad . Try cleaning it out and reconnect .

Okay I've cleaned and reconnected the trans plug the ses light is still on and not flashing the codes when jumping a and b terminals

Thanks for clearing up the injection pump question I didn't know weather it was db2 or ds4. Is there any way to test the tcm? Thanks again guys!

 

[Roberttx13]

The RPM sensor is right at the back of the engine with the fuel line running over it .

I was wondering what that was. Should it show voltage with key on or just running?

 

[Roberttx13]

Should it show voltage at any of the terminals??

 

[EWC]

I'm showing a " Trans " Lamp control circuit from the GAGES fuse . The top right cavity in the ALDL is ground , cavity A . B , or the next one to the left , is the Diagnostic Test . You could have a bad ground in A . Try grounding B with another wire and see if you get codes . Is there a TRANS light in the dash ?

 

[Roberttx13]

Okay I'll try that and no trans light just ses brake and low coolant lights

 

[EWC]

Looking in the shop manual , no Trans light . If you had a P code engine , they call it a Service Throttle Soon . In the speedo , you have a red Brake light . To the right would be Air Bags light if you had them .

 

[EWC]

This is the type of manual I'm using . Ebay 382274175030 .

 

[Roberttx13]

Looking in the shop manual , no Trans light . If you had a P code engine , they call it a Service Throttle Soon . In the speedo , you have a red Brake light . To the right would be Air Bags light if you had them .

Thanks for the information I really appreciate it. I got my abs light to flash 12 when I jump the bottom left terminal to ground but the service engine light still won't flash anything from the diagnostic terminal

 

[EWC]

So , that's good . Means you have a good ground at the A terminal .

 

[EWC]

The manual is showing 5 volts on the ALDL B wire with the key on . Also with the engine running . The B wire is for diagnostics and goes back to the TCM . This is in the purple 24 pin connector , location is A8 and looking at the connectors backview . Color code is white with a black tracer . It is the only wire with this code in either connectors . There are 2 rows and only 1 wire in the corner , A12 . This should be orange and have battery voltage . The next 3 are not used ( A11 , A10 andA9 ) and then A8 . This is the one showing 5 volts .

 

[WarWagon]

2

This is your ECM, trans control module, or whatever you want to call it.

Service Engine Soon means an emmisions control device failed and gov't is holding a gun to OEM's head to turn the SES light on. To lessen warranty claims and who knows... Other non-emmisions failures do not turn the light on. So any codes for transmission problems do not turn the light on.

 

[THEFERMANATOR]

This is your ECM, trans control module, or whatever you want to call it.

Service Engine Soon means an emmisions control device failed and gov't is holding a gun to OEM's head to turn the SES light on. To lessen warranty claims and who knows... Other non-emmisions failures do not turn the light on. So any codes for transmission problems do not turn the light on.

You should say don't always turn the light on. Some DO turn the light on for trans codes.

No, you will not have battery power to your aldl plug. Do not use a truck manual, use a van manual for 95. There are differences between a truck and van. Sounds to me like a power or ground issue to the controller(ECM, TCM, engine or trans controller, whatever you want to call it). GM many times used basically an engine controller for the 4l80e as it needed a good controller to run it with multiple PWM outputs. Failed controllers is not uncommon on obd1 generation controllers. They werenot the best built, and low voltage can kill them in a hurry. I wouldn't worry about anything else until you can get your controller to respond to the code check test. Verify you have power AND ground to all neccesary wires at the tcm. Use a test light with a decent size bulb to simulate a load. I've seen them showvoltage with a dvom, but go to 0 when connected dueto poor connections, so you need to verify the circuit can hold somecurrent load. Next up is unplug the tps, engine speed sensor, trans, and speed sensors. Any shorts to ground can short the controller and prevent it from working. The 1st goal you have to do is to communicate with the controller. If a shorted sensor or input is found shorti,g it, then you have to fix it. If you completely isolate all circuits to the tcm and still can't communicate with it, then theres a good chance you popped the tcm trying to start it with dead battery's. And you need to find out what is killing your batteries to prevent this from happening again.