Help with shift interrupt

Jim O'Connor · Jul 14, 2003

I have a 1988 Four Winns that used to have a 4.3L OMC. The engine died and my mechanic suggested I replace with a 5.0L GI Volvo. I did and I am now having problems shifting. The 4.3L OMC engine had a "shift interrupt module," that connected to the engine. The new(2000) Volvo 5.0L GI does not have an external shift interrupt module. From what I understand, you can tap into a pin comming of the ECM that you ground to provide shift interrupt. My mechanic "rigged" a micro switch to the shift linkage to accomplish this. It doesn't seem to work. I really have to fight to get it to shift. Does anyone have a better suggestion to accomplish this? Are there any after market shift interrupt switches that I could replace this with? Any assistance would be greatly appreciated!

denniz · Jul 14, 2003

Re: Help with shift interrupt

Wow... I understand the swap you made.. Problem is the Volvo sx never used a shift interupt switch.(as you prob. know) I cant think of how to MAKE IT WORK...on a efi 5.0. Id take it back to that mechanic and DEMAND he fix it its his screw-up. If he riggs something into the system he will probably blow the computer... gonna cost somebody big$$$$

Jim O'Connor · Jul 14, 2003

Re: Help with shift interrupt

Unfortuneatly, I think the mechanic may do more harm than good at this point. I believe(from the schematics in my shop manual pin 13 is labeled shift interrupt) that I can ground pin 13 and the ECM will retard the spark, taking load off the out drive. However, I don't like the way he( mechanic ) rigged the micro switch, and I was wondering if I could buy an "in-line" shift interrupt switch to replace his rigging. I'm also not sure that I can do a "hard" ground on this pin, and may need to come up with something to limit current/voltage when the switch is engaged. Would it be a feasible solution to replace the controls and outdrive? I realize it's extreme, but I would assume a new outdrive that matched up with the 5.0GI would come with an appropriate shift interrupt mechanism? Anyone know a technical contact at Volvo or wherever who would be able to provide some guidance?

denniz · Jul 14, 2003

Re: Help with shift interrupt

Volvo tech reps are good but I dont think theyd comment on this... Might make them liable someway. ANYTHINGS worth a try. Youd have to change transom assy. and drive for it to be right. Hate to say this but it sounds like a butcher job. Itd be cheaper to go back carburated at this point with new distributor and old wiring harness.

Ralph 123 · Jul 14, 2003

Re: Help with shift interrupt

When you say "hard to shift" do you mean even going from neutral to gear or just coming out of gear into neutral?

Jim O'Connor · Jul 14, 2003

Re: Help with shift interrupt

Goes into gear (from a dead stop) no problem. Only seems to be a problem when shifting from forward/reverse into neutral. Anyone have any Idea where I can get a schematic for the ECM? I have a block diagram but need to dig deeper to determine what I need to do to isolate the "shift interrupt/Load anticipate" input, so I don't fry the computer.

Ralph 123 · Jul 14, 2003

Re: Help with shift interrupt

check this out: Problem Going Back To Neutral

denniz · Jul 14, 2003

Re: Help with shift interrupt

Just so EVERYONE knows this is a COBRA drive.. Just thought id mention that.

Ralph 123 · Jul 14, 2003

Re: Help with shift interrupt

Rod, do they use the same shift cable type setups or are they totally different?

denniz · Jul 14, 2003

Re: Help with shift interrupt

Volvo sx which is what his motor was built for is a cone clutch drive. Shifting is done in the upper buy a spool between two mating surfaces(w gears) as long as the engine is running coming out of gear is not a problem. (Cable runs straight to the drive from control box) Merc shifting is done in the lower, so is a cobra (not cobra sx .. volvo OMC merger) both merc and cobra had a shift interrupt , 2 different styles, to knock voltage down to the distributor(rpm) to allow the units to come out of gear. The problem is he has a engine and wiring harness that does not allow for this. Cant even idle it down to come out of gear cause its a efi..(ECM)THIS is a tuff one

Ralph 123 · Jul 14, 2003

Re: Help with shift interrupt

ah, I see - totally different. In that case, never mind

(I feel like Gilda Radner on Saturday Night Live years ago) "Ralph you ignorant Sl..."

denniz · Jul 14, 2003

Re: Help with shift interrupt

Just a thought.... Merc still uses a shift interupt with there EFIs....think think think... If I can find a mefi 1 or 2 schematic I should be able to find which wire in the J1 connector is used for the shift interrupt circut.. What computer do you have? are the j1 and j2 inputs on the end parralell with the comp or are they plugged in like a mefi 3? What years a 5.0 GI?

denniz · Jul 14, 2003

Re: Help with shift interrupt

No Ralph..you Cant hurt trying to help

Jim O'Connor · Jul 15, 2003

Re: Help with shift interrupt

Wow, you guys are great!

Jim O'Connor · Jul 15, 2003

Re: Help with shift interrupt

Not sure how to tell what computer I have. On the back of the ECM it has a Delphi sticker. On the top it has 50TBI\00US01 Module AY 3858887. From what I can tell in my shop manual, pin 9 is labled "shift interrupt." I traced it, it's a blue/white wire going into a bobtail plug. There is another wire going into the plug that goes to ground. My mechanic says that when he shorts this, you can hear the engine "sputter." I assume that shorting this tells the ECM to reduce the RPM's taking the load of the cone. Does this sound correct to you guys? I'm just concerned about giving the ECM a "hard" ground, and was thinking of adding a circuit to reduce the possibility of a voltage spike on the ECM. However, I need a schematic of the ECM to determine what to do.

denniz · Jul 15, 2003

Re: Help with shift interrupt

Part # sound like ,And im sure it is a volvo ecm. Dont have a schematic on that yet. What years the motor.. VERY IMPORTANT.. Merc mefi 1&2 USED J1 INPUT #19 terminal for the shift interrupt. when it switched to mefi 3 it went to j2-9. Dont think thats gonna help. Ill try to find it in volvo, which maybe impossible because they never used a shift interupt switch.

denniz · Jul 15, 2003

Re: Help with shift interrupt

Come to think of it I have seen the white/ blue tracer and black wire plug. always left on hooked on a volvo. That may be your answer.

Jim O'Connor · Jul 15, 2003

Re: Help with shift interrupt

The engine was purchased in 6/12/2001, so I would guess it's either a 2000 or 2001

denniz · Jul 15, 2003

Re: Help with shift interrupt

In 2000 Volvo made alot of changes. One is they put there service manual on cdrom...Cant find mine. Illtry to get one.

Jim O'Connor · Jul 16, 2003

Re: Help with shift interrupt

I purchased a set of "shop manuals" from a Volvo dealer. They do contain a wiring diagram and block diagram of the ECM, that does show this shift interrupt plug. Howerver, there is no detailed discussion on it's use. My thought is that I can configure a roller micro switch that is activated by the shift linkage. This switch will be normally open and close when shifting into and out of forward/reverse. I'm just not sure if it's ok to do a "hard ground." I think it may be a good idea to add a varister to avoid a voltage spike to the ECM. This would be a fairly easy mod, however I need to know how much current the input can sink and its operating voltage(5V? or 12V?). I only get one shot with the ECM and I think they cost around $1800, so I don't want to fry it. This is probably overkill, I suspect the ECM has this builtin, but I would really hate to fry the ECM.

Help with shift interrupt

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