Hi all,

I was hoping someone could help me. Im having a no start on my 90 740. It won’t turn over. I have the dash open and the auto gear shifter. I swapped out the neutral safety switch and it didn’t fix it. I’m getting power off the pink wire off the back of the ignition switch but no power off the little wire at the starter. Anybody know what might be going on there?

Thanks,

Chris

 

when you turn the key do you get power at the starter solenoid? if you do try giving it a whack or take the starter apart to see if it's all stuck or replace it.

not the great big wire, that one will have power it goes to the battery, the smaller one.
if your starter energises and it's got it's hot wire from the battery and it's hot, and it is grounded your car should crank.
make sure battery posts are actually clean too, and battery is ok... make sure headlights can turn on bright and normal.

top starter bolt is hard to access but possible. I might have taken off a motor mount and jacked the engine a little, be patient, clean the area first. if no power there it could be a bad keyswitch but you should be able to narrow that down more before trying to swap that. it wont be the key itself, the switch behind the key. id hook a test lamp up to the starter , smaller wire. to ground then your test lamp should light, If it does suspect the starter itself. if not then why is there no power there?

 

I think I’m dealing with two issues. I think my starter gave up. But I’m also not getting power to solenoid. I can’t jump the solenoid consistently to get the motor to rotate but I have randomly got it to turn.

I’m going to pull the starter tonight . But if I’m having power off the ignition I don’t see how i wouldn’t have power at the solenoid wire.

I actually ran a jumper wire from the ignition to the solenoid last night, that of course only gets hot when you crank the key, and the engine wouldn’t turn. That’s why I’m thinking starter is shot. But that solenoid wire it seems like it should have power. What am I missing.

 

First unhook they existing wires from the starter

make sure you have a good ground from the starter to the negative post

use a jumper cable or thick wire and vice grips


connect a second thick jumper between the hot battery post and the big red lug on the starter motor

connect a thin red wire from the hot battery post to positive in the battery

make sure it’s not in gear

you should be able to crank the motor by connecting the red wire to the battery

exclude your other wiring from this test.

all you are doing here is “bench testing” the starter but without removing it from the car.

if the starter is dead you’ll see how those bolt are to get at , you will get them but give yourself time


if the starter functions then connect a test lamp instead of the starter to the red lead Put the lamp where you can see it easy

And if course to battery ground , Then troubleshoot to see why it has no power when you turn your key,

keep the issues separate I think you will find one cause not two causes

Yes the neutral switch can cause this if the starter works don’t get sidetracked but if you have time you can open it and clean and check it out..

almost any older Volvo can share the same starter and they don’t fail often so that should not be a hard to get item . Some are smaller older ones are larger . As long as it works you should be ok

when the solenoid pulls in any the gear engages there are contacts that are made to run the starter . On at least some you can flip them to refresh the contacts..

a poor engine ground can cause no ground to the starter One I had problems with is under the manifold from the alternator to engine block


some 240, have some wires that run around near the front of the oil pan I’d check their condition as they get oiled and heated by where they are That’s likely unrelated just look for now fix that later if they are decomposed


thevproblens coukd be in the key switch or possibly at a terminal near the fuse in tgat circuit but try to tackle it by isolating it’s easier than pulling everything unrelated apart

if the starter was out if the car and on a bench it would be a simple matter to test it I’d try that but with it installed

don’t hurt yourself by forgetting the car in gear you might start it in gear ir the starter can drive the car off a Jack stand so be wary of that

you can connect the wires and then make battery connections and then you won’t be standing in your head

unhook the starter wires don’t backfed them with your jumpers keep it simple like it’s on the bench and out if the car

a meter is fine but you can just make a test lamp with a 12v bulb and a couple alligator clips You can then leave it connected or use more than one this just help simplify things

sometimes with digital multimeters you can get 12 V and not enough potential or amps to do anything a test lamp is hard to fool that way it’s in or off

with a test lamp you can wiggle wires It’s a bit easier to spot a bad connection than doing that while holding probes you might see a lamp flicker wheras seeing digits flutter is less obvious especially if it’s a few feet from you..


I think most Volvo cars of this era can start in neutral or park If I’m in a car that stalled but is rolling ahead a bit with cars behind I might want to start in neutral because park locks the wheels up and you need to be at a full stop to do that

if you drop a tranny one thing that things can get hung up on is wiring to the transmission so it could get tugged and perhaps damaged that way a “ rough” mechanic could twist wires wrap in tape with no solder and then result in problems later so watch for any tape lumps that might show such poor practice Things vibrate so pay attention to any rub or stress points.. if you find any black tape unwrap it and inspect the joint. People do things to get going meaning to go back and do a proper repair.. it happens

 

I ended up pulling the starter and was only getting it to rotate randomly. I exchanged that and put it back in car. Now when I use a jumper wire off the pink ignition to the solenoid I can get it to start with the key. The solenoid is getting no power from the little wire.

 

Do the wires off the ignition and safety switch run under the car? I thought it was all one wire that ran to the blue green solenoid wire but it must have a junction somewhere because it’s hot at the ignition but dead at the solenoid. The car starts now when I jump the starter.

 

when you say you "exchanged" it did you mean you took it in and got a rebuilt one?
when you said you can get it to "start with the key" did you mean the car or the starter started ; -) ? maybe it turned but did not engage with the ring gear?

when the solenoid it is energized it does two things, it pulls the gear in so it can mesh with the ring gear. there is a fork that shifts the position of the armature to make it poke out further and engage.

it also makes contact and causes the starter motor to turn. those are the thick wires, its a big motor so it has a high current draw, that's why big wires and big contacts.
I seem to remember the solenoid has a wire that fits over the bolt that the wire from the car shares. the other end is grounded somehow, to the frame..

if you are having issues or questions just be clear. they tend to be reliable but you could get worn contacts or the armature might get stuck and not shift on a cold winter day. if you took it apart its possible to put it back without that solenoid- armature fork in the right position.

I had once when it wouldn't start in the cold and I almost never rely on mechanics but i had a BCAA membership.. the guy came with a big pipe said ok crank it and whacked the starter with a hunk of pipe, it went,, so I took it to a shop had it replaced. I didn't feel like doing it in the snow.

my girlfriend tried moving my car , I was on the porch watching the show.. , she doesn;t drive really but I thought ok learn.. she turned the key, gave it gas. it started fine but she gave it full throttle and did not release the key. it blew up the gear and fragments went up around the bellhousing and wiped out the TDC sensor and the flex plate with the holes in it that it reads. I straightened it out from under, had to drill a spare 1" hole in the belllhousing by the plastic window vents..

I pulled a starter from a 740 I was wrecking, it was fine. fixing the rest was hard. I was chasing geese all around. I had two bad sensors and took a while to realize the flex plate was all bent up.. no pulse no start, then I got it going, It went a mile , a tow home,, more goose chasing and straightening and playing with sensors. swapped computers all sort sof things since I have parts lying around..
finally I think it was just a bad coil connection , one of the little wires there.. Im hoping its that and not an intermittent somewhere else. Ill find out in time, it starts I need to drive it now. Ill clean wires but hard to troubleshoot every possibility when it works..

It looks a bit like it fell out of a mad max movie with half the clearcoat missing, good tires, Heater motor works, perfect winter beater;-) windshield leaks.. Im going to try to fix that with just goop.. Ill post on that.
some cars have a separate solenoid and the starter enguages with a bendix. I always hated the design, all the redblocks used this type of starter, Its solid.. I bet what my girlfriend did would kill any gas car. first time I realized just how easy it is to just get in and ruin a car in about 3 seconds.. it was an accident, Just ill informed. It didn't feel that way when it happened or when I was chasing geese.. I'm happier now though ;-) one reason I wanted it to go was so she doesnt; wreck my other volvo's its a perfect car to learn on. lesson 1 let go of the freakin key..

pre about 89 doesn't have the TDC sensor, it was in the distributor, it causes problems there too.

 

I’m chasing a blue green wire that connects at solenoid into the cab. It has a connection at the firewall and I can tell now power is not leaving the cab.

 

so if Im deciphering this right , your key works because you found power at the contact that's activated when the key is turned to the start position.

it has the ignition wire, thats ok because if it did not the computer couldn;t work, but you said the acr runs.

so we move focus to that key wire in the run position.
off the top of my head I cant; think wha else the start position wire would power. maybe it gets spark onthe first revolution or something before the computer reads its position. it can fire right away but it can;t read TDC until it passes the sensor by the blank spot. at the first moment you turn the key the computer is blind as to what position the engine is in. on mine I just had it so It wouuld fire on the first revolution but not run which still mystifies me.. once the comuter initializes its tracking that pulse and coordinating the position and its happy doing its thing and cooperating with the ignition computer
i remember on older cars there was a ballast resistor that could fail and that would cause that condition but that was with a points system...

I had a link to volvo wiring diagrams but I just noticed it was pulled. maybe some copyright reason, but I thought they were released.. do you have a link to the proper schematic for this year?

there is some wiring that enters down near the shifter, some might run under the console or under the carpet. we need to follow tht key wire and look what else is involved between the key and ignition. , if we are on the right path here, If its runig through a harness lets see whats involved. you want the reason for this failure, then you can be satisfied of the repair.. the fix will be easy.

last summer I took a 740 wagon apart, 1988 I pulled alomost every wire out and its in a box like that. it had a lot to do with electric windows and stuff power mirrors.. between tht and yours they introduced the bellhousing timing sensor so that was a significant change. the ICU is different. the computer might swap, turbos had some other features on the ECU I think. because the ECU is different , Id consider it a bit of a different beast. the harness will have differences. best to start with the correct diagram. I have never had a key switch failure. doesn't mean they cant fail.

 

by cab did you mean cable or cab like the cab of a truck IE the passenger compartment?
if you found a connection at the firewall , that's promising. is there continuity through that wire and the connector? maybe don't unplug it if you can get to either end of the wire just so that way you can check to see if it's an issue there at the connector. If you PROVE it is there you solved it. If you clean the connector t still means you probably solved it I guess, once you know what it is it will be a happy moment. cleaning a plug or bypassing it will be a walk in the park , its just nice to know for sure.

at first I thought it was a 240 starter same thing/ different shape, pretty much, but the top bolt might be easier on a 740.. last one I pulled by dropping the engine and trans and crossmember on the ground so then removing starter was a non issue.

sounds like you pretty much got it..

 

Yes I can get the car to start and run now by using a long wire with an alligator clip on each end. I clip one end to the pink wire off the ignition switch and the other to the solenoid. So I may just soldier that in but I really want to know exactly what is causing the issue.

My latest move has been to start at the solenoid and work backward trying to follow that blue green wire through the wire harness. I’ve been cutting the harness open in spots chasing this thing and it gets to a plug junction up by the drivers side windshield at the fire wall.

I see what your saying I should reconnect that junction and back probe that wire so I can see if voltage is getting to that point when I crank the engine.

Im just a diy guy so I struggle with this stuff. But I’ve been able to do quite a bit in the past did the head gasket on this car about 70 k ago.

 

Dont have a diagram that old perhaps an early 940 is similiar.
Should have 12v on Pink from the start position on the ignition switch to the NSS, to the blue when in park or neutral, That changes to a blue green wire and goes through connectors c2 and c51 illustrated below.

 

Thank you for the diagram. I couldn't really tell where c2 lived so I ended up just running a new wire. I bought that used wagon when my son was in Kindergarten now he is a senior and he has been driving it these last two years. I'm hoping we can get him through his senior year with it. 230 k. Still going.

 

what's that thing labeled as 15-1 ? pic is a little fuzzy but it looks like maybe a little plastic junction box. why the box? FUSE INSIDE?

looks like they are showing two red wires from the ignition switch , through that , to the starter solenoid, that's the hot side, the return path to ground also being switched through 3/40 which is the neutral / park switch near the shifter.

makes sense , both the key and the shifter need to be in the correct position to complete the circuit and energize the solenoid.

once solenoid energizes the motor cranks, that's not a problem.

you seem to be jumping that path from key to starter and succeeding so the solenoid does seem to be grounded through the shifter switch.
just for fun try this :

if you can't find that box where the diagram shows try looking near the strut tower for a little white box and some fairly thick red wires. if you find it, see if you can open it to check inside.

maybe it is a service connection to crank the engine , to check for spark etc, as its hard for a mechanic to be at the key and do a compression check .. looks like if you connected there to hot in there, you'd jump the key , maybe with a button to crank it, and a battery clip.

the box must have reason. they could have simply spliced those wires..

 

I found C51 and it’s just a junction that has wire coming in and wires going out. Blue green to the solenoid is there. I separated it and tried to see if I was getting power there and from what I could tell I wasn’t. It’s under the diagnostic box.


So I then tried to find 15/1 thinking it might be under the fender I pulled the fender liner. Nothing there. So I’m assuming it’s inside the car under the driver side dash up in the corner. There is a tangle mess of wires there Bc I think that is where the cpu lives. And at some point this thing had an after market alarm.

I didn’t want to dig any deeper Bc it’s too difficult working upside down under the dash looking for a mystery 15/1. I don’t really like it but I feel like I got a good splice on my introduced wire, a new neutral safety, and a new starter. All this has been compounded by the fact that I work alone and that solenoid needs crank power at key to energize.

Thank you for your insights.

 

Black plastic Junction box with various size B+ wires wth spade terminals. Volvo uses them in many of that era cars.