I'm missing something here. I'm simply trying to trace a wire off of the fuel pump relay.
In the diagram, the fuel pump relay is 2/23. I'm trying to trace the wire coming off of the 31b terminal of the relay, which should be a switched ground. The diagram sends it off to "C". My problem is trying to figure out just exactly what is "C".
I've attached a pic of the diagram, and here is a link to the entire wiring portion of the service manual for reference. http://www.volvowiringdiagrams.com/volv ... agrams.pdf
If I can just figure out what C is I'd be golden, but I'm lost and have gone through every single page of the PDF trying to figure it out with no luck.
I tracked down all of the Y-GR color wires as well and it's not helpful. One goes from the instrument panel to a connector and then to the fuel level sensor, but between the sensor and connector it is a W wire, not Y-GR like it is between the connector and instrument panel. The second one travels from 2/76B:3 (2/76 is listed as the Control Module Central Locking / Anti-theft Alarm) through connector 24/3C (which is listed as firewall cable harness - left door sill cable harness) on to 7/100:1. component type 7 is a sensor. But I can not find sensor 7/100 listed anywhere, so no idea what it is.
So to end with a couple of concise questions:
1. What is "C"?
2. What grounds 31b on fuel pump relay 2/23? Is it possibly grounded by the anti-theft system via 2/76?
3. The fuel pump relay is a 15/87/31/31b. 15 switched input (12v) from ignition. 87 is output to fuel pump. 31 is battery ground. 31b is switched ground (to what is the mystery). My question here is regarding the behavior of this fuel pump relay. Is the relay closed and providing 12v through 87 when 31b is grounded, or when it is not grounded? I'm not having any luck locating this info.
Get email notification of topic replies. Log in or register (free). Amazon Link Buy anything with this and it helps MVS!
Question on Wiring Diagram
-
- MVS Moderator
- Posts: 14798
- Joined: Thu Sep 07, 2006 8:24 am
- Year and Model: Many Volvos
- Location: USA Midwest
- Has thanked: 4 times
- Been thanked: 56 times
Re: Question on Wiring Diagram
C directs the circuit to the next page. The corresponding C will be on the left hand side of the next page.
...Lee
...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe
- sleddriver
- Posts: 975
- Joined: Thu Apr 08, 2010 6:06 pm
- Year and Model: 1998 V70 T5
- Location: Tx
- Has thanked: 11 times
- Been thanked: 12 times
Re: Question on Wiring Diagram
The diagram you posted in on page 86 of the manual, which is page 17/133 of the pdf . The missing page you are seeking is on page 87 of the manual, which is page 106/133 of the pdf. A bit confusing when ordered that way........
Hope that helps....
Hope that helps....
1998 V70 T5 226,808 miles. Original Owner.
M1 10W-30 HM
M1 10W-30 HM
-
- Posts: 16
- Joined: Sat Feb 27, 2016 10:58 am
- Year and Model: 1999 C70 Turbo 2.4L
- Location: Montana
Re: Question on Wiring Diagram
31b on the fuel pump relay runs to B45 on the ECM. So I would then assume that the ECM grounds this line to trigger the relay and start the fuel pump? And if I'm correct in that thinking, if the ECM is doing it's job here, I should have continuity from 31b to GND when key is in II, and an open circuit when the key is off?
- abscate
- MVS Moderator
- Posts: 23751
- Joined: Sun Feb 17, 2013 5:54 pm
- Year and Model: 99T5 ,99S70,2005V70
- Location: NYC, ALBANY NY
- Has thanked: 443 times
- Been thanked: 1338 times
Re: Question on Wiring Diagram
Welcome to the complexity of fly by wire cars....ugh
You can't always assume 31 is a battery ground, it's a ground function, but not necessarily a ground. The ECU is not just a simple switch to ground so you can't assume a simple check of that reminds to ground confirms operation.
Trace it from your fuel pump relay to C, and then , if I recall it actually gets ported to the throttle position switch where it probably ( total guess) gets processed as a throttle unloading or full throttle cutoff switch or something, which sends a signal to the ECU for actual grounding.
Be careful putting signals ( which includes measuring voltages and continuity ) on ECU connected stuff. It is sensitive to static discharge as well as voltages it isn't expecting.
You can't always assume 31 is a battery ground, it's a ground function, but not necessarily a ground. The ECU is not just a simple switch to ground so you can't assume a simple check of that reminds to ground confirms operation.
Trace it from your fuel pump relay to C, and then , if I recall it actually gets ported to the throttle position switch where it probably ( total guess) gets processed as a throttle unloading or full throttle cutoff switch or something, which sends a signal to the ECU for actual grounding.
Be careful putting signals ( which includes measuring voltages and continuity ) on ECU connected stuff. It is sensitive to static discharge as well as voltages it isn't expecting.
Empty Nester
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 BMW
Link to Maintenance record thread
Link To Volvo Glossary
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 BMW
Link to Maintenance record thread
Link To Volvo Glossary
- abscate
- MVS Moderator
- Posts: 23751
- Joined: Sun Feb 17, 2013 5:54 pm
- Year and Model: 99T5 ,99S70,2005V70
- Location: NYC, ALBANY NY
- Has thanked: 443 times
- Been thanked: 1338 times
Re: Question on Wiring Diagram
If 7/51 is the TPS my WAG was actually correct .....
Empty Nester
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 BMW
Link to Maintenance record thread
Link To Volvo Glossary
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 BMW
Link to Maintenance record thread
Link To Volvo Glossary
-
- Posts: 16
- Joined: Sat Feb 27, 2016 10:58 am
- Year and Model: 1999 C70 Turbo 2.4L
- Location: Montana
Re: Question on Wiring Diagram
According to the diagrams it is just a straight connection (no connectors or anything between) from 31b right to the ECU. Any thoughts on how to check this?abscate wrote:Welcome to the complexity of fly by wire cars....ugh
You can't always assume 31 is a battery ground, it's a ground function, but not necessarily a ground. The ECU is not just a simple switch to ground so you can't assume a simple check of that reminds to ground confirms operation.
Trace it from your fuel pump relay to C, and then , if I recall it actually gets ported to the throttle position switch where it probably ( total guess) gets processed as a throttle unloading or full throttle cutoff switch or something, which sends a signal to the ECU for actual grounding.
Be careful putting signals ( which includes measuring voltages and continuity ) on ECU connected stuff. It is sensitive to static discharge as well as voltages it isn't expecting.
-
- Similar Topics
- Replies
- Views
- Last post
-
- 0 Replies
- 602 Views
-
Last post by legalstuff
-
- 8 Replies
- 351 Views
-
Last post by Batty251
-
- 2 Replies
- 246 Views
-
Last post by abscate