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Old 06-23-2019, 05:29 PM   #1
nickvolvo746
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Default wiring diagram help 760

1990 760 turbo b230ft (lh2.4?)
who's got a wiring diagram for this? I couldnt find anything on the wiring diagrams thread that fits the year. Specifically dealing with the injection system.

Also, has anybody had problems with fuses burning out and instead bypassing the fuses alltogether? I somehow dont have fuses in the two slots for fuel pump and injectors and the slots look burnt. Had the car for over a year like that and it wasnt a problem so the PO must have done some tricky wiring, I am thinking that is where the solution to my problem lies.

Thanks in advance if youre reading this, youre making my day.
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Old 06-23-2019, 08:23 PM   #2
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1990 760 turbo b230ft (lh2.4?)Specifically dealing with the injection system.
LH 2.4 is LH 2.4

http://www.volvotips.com/index.php/7...repair-manual/
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Old 06-23-2019, 08:56 PM   #3
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thanks mate,
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Old 06-23-2019, 09:19 PM   #4
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Rummage around and either Oz or Wayback Machine of volvowiringdiagrams should have a Mitchell's "Volvo 740 1989 Wiring.pdf" and a Volvo Greenbook "TP31075-1 1988 760 Wiring Diagrams.pdf". Those are the closest I've seen.

The turbo injectors will have a resistor pack (front left inner fender?) and a radio surpression relay (RSR). I'm not familiar with 760s, but the RSR is probably near the coil or front left shock tower. If you find the resistor pack, you should be able to trace the center wire to the relay.
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Old 06-23-2019, 11:22 PM   #5
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If you can't find it online, I have a copy of the '90 760 manual that I scanned and used to be online before volvowiringdiagrams crapped out. Shoot me a PM with your email address and I'll send it to you.

The wiring harnesses in the '90 models can be a real pain. I spent the better part of a weekend getting a friend's 760 sorted out. IIRC there was power on one side of the fuse panel, but not on the other even with a good fuse. It's been a few years, but I do remember that it took a long time to get sorted out.
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Old 06-24-2019, 12:12 AM   #6
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http://borich.lesnoe.spb.ru/auto/Vol...ngDiagrams.pdf
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Old 06-24-2019, 12:42 AM   #7
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Thanks!
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Old 06-24-2019, 07:25 AM   #8
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Yes, thank you . . . again . . . Hiperfauto!

If you will shorten the link to only: borich.lesnoe.spb.ru/auto/Volvo/GreenBooks/

You will have a long list of Greenbooks in .pdf format for 700 series cars for your personal collection.
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Old 06-24-2019, 05:41 PM   #9
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diconnected AMM and no fuel relay buzz, no pump on and no start. What does this tell me, if anything?
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Old 06-24-2019, 10:25 PM   #10
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...no pump on and no start. What does this tell me, if anything?

bobxyz hinted "radio surpression relay (RSR)" If this relay is not activated, then a no start condition.

LH 2.4 only turns on fuel pump (1) for a few seconds when key is switched on, and (2) when engine is rotating. But, item 1 does fail, so only item 2 works.

I'll look at diagram later tonight....I've been busy for past 13 hours today.

Focus I think is,

1. Is there spark?

2. Are injectors pulsing?
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Old 06-24-2019, 11:49 PM   #11
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Using PDF that hiperfauto provided, and on PDF page 18 (page 20 Adobe), is the 2/12 Relay interference suppression relay shown bottom right to injectors.

Does pin 3 (GR wire) have power when ignition switch is initially switched on, or when engine is cranking? Also, check pin 2 (BL-Y wire)...same way.

2/12 is powered up by 2/13 fuel injection relay, which is know to fail.
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Old 06-25-2019, 11:36 AM   #12
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Quote:
Originally Posted by 84B23F View Post
Using PDF that hiperfauto provided, and on PDF page 18 (page 20 Adobe), is the 2/12 Relay interference suppression relay shown bottom right to injectors.

Does pin 3 (GR wire) have power when ignition switch is initially switched on, or when engine is cranking? Also, check pin 2 (BL-Y wire)...same way.

2/12 is powered up by 2/13 fuel injection relay, which is know to fail.
If the GREEN wire doesn't have power during cranking or running, then the injectors won't run. So I would say yes, it should have power. It gets that power when that 2/12 relay closes.

And of course the BLUE/YELLOW wire is the one responsible for closing it. So the answer is also YES.

So get your test light out and check which wires ACTUALLY have power.
Dave
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Old 06-25-2019, 01:00 PM   #13
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Originally Posted by 84B23F View Post
bobxyz hinted "radio surpression relay (RSR)" If this relay is not activated, then a no start condition.

LH 2.4 only turns on fuel pump (1) for a few seconds when key is switched on, and (2) when engine is rotating. But, item 1 does fail, so only item 2 works.

I'll look at diagram later tonight....I've been busy for past 13 hours today.

Focus I think is,

1. Is there spark?

2. Are injectors pulsing?
I do in fact have both, the problem is lying somewhere in the fuel system for sure. Heres why I know or think that (granted, im a noob so im open to criticism). The fuses slots for fuel injection and pumps are both burnt and did not have fuses in them the entire time Ive had the car. I found under the dash the solution the prevous owner rigged up. He basically has the fuses wired into these funky little DIY boxes. I posted a link that I hope work to show a picture. Clearly, these fuses have had wiring problems in the past and they were simply kicking the can down the road for me to deal with it now. So, ****ty wiring throughout the fuel system is my guess.


https://drive.google.com/file/d/1FXx...ew?usp=sharing
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Old 06-25-2019, 01:04 PM   #14
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If the GREEN wire doesn't have power during cranking or running, then the injectors won't run. So I would say yes, it should have power. It gets that power when that 2/12 relay closes.

And of course the BLUE/YELLOW wire is the one responsible for closing it. So the answer is also YES.

So get your test light out and check which wires ACTUALLY have power.
Dave
Checking all that right meow. Relay definitely isnt the problem and I deff have spark and all that. Radio suppression relay also seems fine. Im thinking the problem is ****ting wiring or grounds, or potentially a funky ecu. My plan is to completely bypass the whole thing by rigging up my own set of relays and switches for the tank pump and inline pump. This way when I get in the car, I can hit two switches to turn on both pumps, and I will be able to make sure the wiring and grounds are A+. What do yall think of that idea? Will I be able to run the car like normal doing that? I would basically be ignoring the whole fuel injector relay and wiring and going straight to the horses mouth.
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Old 06-25-2019, 01:09 PM   #15
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Here is what I found under the dash that the PO used to get around the problem which I assume is related or the problem itself. He probably got sick of trying to figure out where the gremlin is.

https://drive.google.com/file/d/1FXx...ew?usp=sharing

ignore all the BS on the floor there, just ripping out the radar detector that apparently was an option with these cars.
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Old 06-25-2019, 01:19 PM   #16
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That looks like it could be an OK repair. The fuses get hit from poor tension on the terminals and from fretting. Then the holder melts. Next you gotta rebuild the circuit. At the shop I get new terminals and build a new circuit.


Does it run yet? I cant keep track of where youre at with this.


Do NOT RUN A SWITCH FOR THE PUMPS UNLESS YOU WANNA BURN ALIVE AFTER A CAR ACCIDENT.
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Old 06-25-2019, 01:30 PM   #17
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Try finding wiring diagram for 1991 Volvo 940 SE (1991 Volvo 960 Turbo) if you're unable to locate one for 1990 760 Turbo.
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Old 06-25-2019, 01:31 PM   #18
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Quote:
Originally Posted by nickvolvo746 View Post
I do in fact have both, the problem is lying somewhere in the fuel system for sure. Heres why I know or think that (granted, im a noob so im open to criticism). The fuses slots for fuel injection and pumps are both burnt and did not have fuses in them the entire time Ive had the car. I found under the dash the solution the prevous owner rigged up. He basically has the fuses wired into these funky little DIY boxes. I posted a link that I hope work to show a picture. Clearly, these fuses have had wiring problems in the past and they were simply kicking the can down the road for me to deal with it now. So, ****ty wiring throughout the fuel system is my guess.


https://drive.google.com/file/d/1FXx...ew?usp=sharing
You may want to sort this mess out.
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Old 06-25-2019, 01:39 PM   #19
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Fuel relay buzzing is related to a poor ECM grounding circuit to the relay.
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Old 06-25-2019, 01:41 PM   #20
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Quote:
Originally Posted by ZVOLV View Post
That looks like it could be an OK repair. The fuses get hit from poor tension on the terminals and from fretting. Then the holder melts. Next you gotta rebuild the circuit. At the shop I get new terminals and build a new circuit.


Does it run yet? I cant keep track of where youre at with this.


Do NOT RUN A SWITCH FOR THE PUMPS UNLESS YOU WANNA BURN ALIVE AFTER A CAR ACCIDENT.
yeah sorry, I post too much on here. Apparently you cant delete threads? Yeah im a dumbass and already posted another one about specifically the the switch thing. I see what youre saying about the pumps running after a crash. Obviously that sounds like a terrible way to go out but, is there no way to rig it so that they auto shut off? or is that where you would say just do it the right way in the first place
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Old 06-25-2019, 01:41 PM   #21
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Try finding wiring diagram for 1991 Volvo 940 SE (1991 Volvo 960 Turbo) if you're unable to locate one for 1990 760 Turbo.
someone hooked me up the other day, thanks
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Old 06-25-2019, 01:43 PM   #22
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Quote:
Originally Posted by ZVOLV View Post
That looks like it could be an OK repair. The fuses get hit from poor tension on the terminals and from fretting. Then the holder melts. Next you gotta rebuild the circuit. At the shop I get new terminals and build a new circuit.


Does it run yet? I cant keep track of where youre at with this.


Do NOT RUN A SWITCH FOR THE PUMPS UNLESS YOU WANNA BURN ALIVE AFTER A CAR ACCIDENT.
oh and no it does not run yet. I have been learning a lot over the last 48 hours though. Havent started the new job yet so ive basically done nothing but comb through the car and do endless amount of research on this problem and on elctrical stuff in general. If i want to be kewl like you guys ill have to learn how not to post a thread on here everytime my sh!tbox doesnt like me.
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Old 06-25-2019, 01:49 PM   #23
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Fuel relay buzzing is related to a poor ECM grounding circuit to the relay.
from what I have always understood there is one ECM to rule it all and in the darkness make the car go vroom. on the wiring diagram, I found labels for "Controll unit ECC" and "control unit lh2.4" and then "control unit lh2.4". What exactly is meant by all this? I take it from the diagram that "control unit lh2.4" means the main computer, but are the other labels just talking about wiring going to said computer, or about separate systems hooked into one? I apologize for the probably dumb question.
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Old 06-25-2019, 01:51 PM   #24
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ECC is the climate control unit. LH 2.4 is the fuel system, EZK is the ignition system. Finding Mitchell wiring diagrams will break the diagrams down by system.
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Old 06-25-2019, 01:54 PM   #25
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ECC is the climate control unit. LH 2.4 is the fuel system, EZK is the ignition system.
doh, ok cool. So the EZK ignition system is a separate computer from the ECU/ECM?
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