My 87 d150 with the 904 lockup converter isn't locking up.I still have the ESA computer and I don't know how to trouble shoot this.I do know that the blue wire on the trans is hooked up and the relay is still there.Can anyone point me in the right direction?

Can you photograph the wire where it comes out of the transmission and where travels up to the spark control computer? I have heard that some 1987 Dodge trucks and vans were equipped with a computer controlled lockup torque converter but I have never seen one documented.

To answer your question, most likely the ESC has failed. They are notorious for doing so. They are also hard to find replacements for and expensive to repair.

The absolute best thing you can do to help you troubleshoot is to get a factory service manual. y 1987 the systems were getting complex enough that you need the factory diagnostic instructions to troubleshoot.

I don't have a pic but it is a single blue wire connected to a solenoid on the upper left side of the pan.The other plug is for reverse lights and nuetral safety switch and one other unknown to me wire.The blue wire ends at a relay by the left hood hinge.The 87 is a computer controlled lockup.I can get a Cardone ESA computer from Summit for around $150.00.It is worth it to me to have the lockup feature for highway driving.I also don't think the timing is advancing so I should buy one!!

The lean burn computers are notorious and picky. You MIUST have all the sensors and vacuum hoses hooked up correctly and you MUST follow the factory procedure for setting the timing and carburetor. I don;t know if the lockup is something to lose sleep over. It helps a small bit on the highway, but only 5-8% or so. However, the ESC also controls the timing and carb, so if it has failed it should be replaced.

My truck has no O2 sensor or feedback carb.I only have the idle solenoid on the carb plus the mini cat on the exhaust pipe below the manifold(not for much longer)The only thing missing on this truck is the A/C and air pump.Gonna order the ESA on Monday.

Does your distributor have a vacuum advance canister? If not, then the computer controls your timing advance.

I have the ESA computer with the vaccum line hooked to full manifold vaccum.

Then the ESA controls your timing. You might want to use a timing light to see if you have advance function or not. If not then I'd check the wires to the ESA & see if all powers, grounds, & inputs are there before tossing a new ESA in. If it has a temperature switch or sensor- that might have gone bad & could limit advance & disable lockup. You'll need to track down a wiring diagram- FSM.

On lockup control- I'd (carefully) wire in a test light to the blue wire from the relay so you can watch it while driving. Then go on a test drive - if the ESA is triggering the relay you'll see it. If the relay powers up the LU solnoid but it doesn't engage the clutch then you know it's likely a fault inside the trans.

_________________
63 Valiant Wagon
225 - 4 bbl

I have set the timing per the underhood sticker at 16 degrees.If I rev the engine it stays at 16 degrees.This makes me think the ESA is not functioning. As for any switches I don't see any but that doesn't mean there aren't supposed to be some

There should be at least a coolant temp sensor and a intake manifold air temp sensor. There must be a vacuum line from the computer to the constant vacuum tap on the carburetor. The vacuum transducer on the computer must also hold a vacuum. For the computer to function properly, ALL switches must be present and functioning and the vacuum line and transducer is critical.

Here is a diagram of all the switches you must have and where they are located:



If the timing is not advancing there is a problem somewhere. Verify that you have all the switches and the vacuum transducer on the computer actually holds a vacuum and that the vacuum line to the computer goes to a port on the carb that provides constant manifold vacuum.

If all of those things check out, then it is time to get a factory service manual for your vehicle and follow the troubleshooting guide in the manual for the lean burn system.

Thanks Reed for that diagram.I have all those things hooked up sans the Vaccum switch next to the temp gauge sending unit.I don't know if this has any bearing on my problem but it is still there with no lines going to it.FSM here I come!

BTW te transducer holds vaccum but smells and tastes like gas when I tested it.Don't know if that matters but there it is.

BTW the transducer holds vaccum but smells and tastes like gas when I tested it.Don't know if that matters but there it is.