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Hello, I know there has been several posts about this but about all of them say something a little different. 86 with the 4+3. I just bought the car and the guy said the transmission and overdrive were rebuilt but he was fighting with the transmission shop as overdrive was not working properly. How do I bypass the ecm to see if it is actually the overdrive unit or the ecm? I have read several posts one says to cross A7 and C8 I believe, one says to run a fused hot wire on a switch straight to the solenoid, then another one says something else. I replaced the relay and the button on the shifter will turn in and off the light on the dash. She is also very hard to shift into 3rd and 4th. Third mainly.
any help would be appreciated.
On an 86 specifically: If the lamp is working then the shifter switch, ecm and relay are functioning as intended. The issue is therefore with the pressure switch, solenoid, related wiring or mechanical.
I called the shop that rebuilt the overdrive before I bought it and he said he replaced the solenoid but a few of the clutch discs were not very good but he could not get them to replace them. The button was working and would turn the light off and on but is not now. I willl mess with sone wires tomorrow to see if I can get it working again. Not certain why he could not get the clutches as I have seen several complete rebuild kits with all of the clutches for about $200. He did say that the car had sone electrical issues which I am trying to fix. But from the reading and suggestions that you gave me it looks like I could possibly hook the green wire that goes to the overdrive to a hot wire with a switch to bypass the ecm. Is that correct? That will let me have the overdrive while I am still working in the electrical bugs. Also are these overdrives that hard to rebuild? Does not look like there is too much there just make sure it is all taken apart and put back together correctly.
With an 86, I'm pretty sure that the coolant temperature must be above the 122 °F enable threshold before it will allow you to disable OD via the switch. This may explain the varying lamp/switch behavior that you have observed. Try it with coolant temp above 122 °F.
No difference. It does look like they have the tan and black and maybe black and blue crossed/wired together at the relay but still going off to where they are supposed to go.
Overdrive bypass
