I havent had any issues with my dash besides for my front fuel tank not reading on the guage cluster. I was going to replace the guage cluster but I'm not sure if I want to go all digital or if I stick with the OEM style.

 

I've had a harsh shift periodically ever since I've owned my '91. Usually if I'm accelerating hard and its between 2nd and 3rd. No codes whatsoever. I need to check that connector.

Any comments?

 

that's pretty much the same issue I'm having. The p/o said the trans was rebuilt so im not sure exactly if it was or not and im showing a 624 code. I'm waiting for a harness replacement to come in the mail but my current harness doesnt have any corrosion that I can see. This weekend I'm gonna take a in depth look at the harness and see what I find out.

 

Same here. These E40Ds are notorious for this. It would be nice to know its the connector. But why mostly between 2 & 3? That doesn't sound like a connector. I've just finished headers, plugs, throttle body clean, EGR and more and the truck is running well other than this.

 

[QUOTE=Gee150;19303489]Same here. These E40Ds are notorious for this. It would be nice to know its the connector. But why mostly between 2 & 3? That doesn't sound like a connector.


I understand completely. I've been at this issue since buying the truck. I'm hoping that its just the wiring but I cant seem to figure out why that would be causing the shifting issue. As soon as I figure out what fixes my issue I'll be sure to let you know what I figure out.

 

Can a faulty TPS create a hard shift? I've never changed mine. I have to do the lower intake and I do intend to test it

 

I found this video interesting
Clearly, as pointed out by MARK, the solenoid is key but sensor feed to the ECM is also important and that CONNECTOR as pointed out earlier in the thread. Pity we don't have OBDII. Can techs with more sophisticated readers get more information through the OBDI hookup even if the system is not showing any codes?

Another question - can any sensor act up a little, not generate a code but impact the ECM signal to the Tranny - causing a hard shift? A TPS for example when the throttle is opened wider? I only get a hard shift at higher rpms.

 

I had a 93 with the same problem, ended up being the valve body housing the shuttle valves in the bottom of the trans. I had the E4OD also. It literally felt like it had a shift kit. Not saying that's definitely the problem, just being forthcoming with some info. Hope you find the problem. I like that body style for those years. Mine got totaled at an intersection in 2005 with 250k miles on it. All I ever replaced on that truck was that valve body, an alternator and a water pump. Oh, and shocks and brakes. Normal wear pattern stuff. That old 302 ran perfect and didn't burn any oil.

 

First you will need to get pinout charts for the PCM and the E40D connectors. They are in the EVTSM Manual (Electrical and Vacuum troubleshooting Manual) if anyone can post them, or you might Google them. I have them for the 1991 but I'm not sure about your model. You'll need to do continuity tests from the PCM connector to the corresponding pins on the solenoid connector.

Mark - on the '91 E40D pinouts it shows one connector for Solenoid #1 Shift signal and another for Solenoid #2 signal. Can you shed light?

 

It can, but it wouldn't set a code 624. So that tells me that the TPS is not the problem here.

 

So what could cause a hard shift between 2&3 at more aggressive RPMs but not set a code (my occasional problem).

 

Code 624 is your problem. That could be a bad EPC (Electronic Pressure Control) solenoid or a problem in the wiring between the PCM and the EPC.

 

After purchasing my truck, I had multiple trans codes with the 624 being most prevalent for years.

Also hard shifts of varying intensity which came & went without any resetting of the computer. (pulling bat. power)

Finally with the onset the truck slowing randomly from a constant speed with no corresponding change of RPMs (slippage) on multiple occasions with NO codes related to the trans, I had it rebuilt.

The problems remained. After a series of "unfortunate events" including wiping out the thrust bearings of the 5.8 & it's subsequent rebuild, there were still shifting issues.

That's when I opened up the ECU to discover leaking capacitors. Had them replaced & immediate improvement was result, but not 100%.

Subsequent issues were finally resolved by replacement of the PSOM as well which was not showing leakage of it's capacitor.

Yes, the bouncing of the speedo needle at low speeds was resolved at that time as well.

My advice to anybody with E4 issues is to follow much of the good advice listed in the posts above, but also open up the computer first thing & start grabbing a handful of 94-96 PSOMs from the junkyard.

As always, your results may vary & the advice offered is worth just what your paying for it.

Good luck.

 

Mark - On my '91 5.8 I do not have any codes. So it could be the TPS, correct? Also can the solenoid act up without setting a 624 code?
What's you opinion on the shift issue being between 2-3?

There are 3 codes in the OBD1 code list for shift errors -
617 - Transmission problem 1-2 shift error
618 - Transmission problem 2-3 shift error
619 - Transmission problem 3-4 shift error
What generates these codes?

 

I suppose it could be the TPS. It should set a code, though.

The EPC can act up without setting a 624 code. But I thought you said you had that code.

The shift error codes set when the PCM commands a shift but does not see a corresponding RPM drop.

Mark