Making a Diagnostic Test Box for the 940

[lester08]

The late version 940's did not have an under bonnet diagnostic box, instead there is a OBD II style connector in the cubby with a clip-in cover you can prise out with a screw driver.

Thanks to Jod T5 who provided the basic circuit and instructions http://www.volvoforums.org.uk/showthread.php?t=46943 and to davidwad for telling where the socket was and for general help thanks to Chris_Rogers.

Although you can manage with paper clips and a multimeter it is a lot easy to work with a correctly made box, so I thought I would share the parts and construction info for my little gizmo.

Below I'll post the modified circuit diagram, I have added a switch to select Ignition or Fuel system read out and added colour labels for the wiring. Next post I'll list the parts and suppliers used, some construction info and a few photos.

Total cost was £27.25 + 2 hours build time.

Tools Required

1. Soldering iron and solder with flux core
2. Wire cutters.
3. Wire stripper or sharp knife
4. Pair of needle nose pliers
5. hand drill and assorted wood/metal drill bits
6. Small Philips/Cross head screwdriver for the box lid and connector case.

Parts List

Supplier SKPang electronics
http://www.skpang.co.uk/catalog/prod...products_id=93

OBD II Connector £10.58 + £2.70 P&P

Supplier Maplin Electronics
http://www.maplin.co.uk


Part .. Description .......... Qty .... LineTotal
===================================
XS42V 9 Way Cable .......... 2 ..... 2.38
JZ43W Cable Exit Gland ..... 1 .... 2.99
YY40T LED Clip 5mm ......... 1 ... 0.15
FH00A Sub-Min Toggle A ... 1 ... 2.29
JM01B Sub Min Push Sw Blk 1 ..... 0.99
WL27E 5mm Red LED ........ 1 ...... 0.29
M1K8 .. Min Res 1k8 ........ 1 ..... 0.15
N68FK . ABS Box 85x56x36 . 1 .... 1.49


Total £11.43 + £2.54 P&P


Drilling Info

Hole ....... specified mm ... Used
============================
Grommett.........15...........~16mm
Switch main......6.2........1/4 inch
Switch lock......2.4..........3mm
Button.............5.0..........5mm
LED Mount........6.35.......1/4 inch


Notes

[1] I used a 2 metre length of cable but less would be OK.
[2] The Cable Exit Gland and OBD II Connector are specified for a 5mm dia cable but the 6mm dia cable used fitted OK.
[3] I connected the cable screen to the ground/0V pin at the connector as well as the black wire, leave the box end of the screen disconnected. A screen is probably not needed but I felt it was good practice.
[4] To find the components on the Maplin site enter their part code in the search area at the top. Each components page will have drilling and other info.
[5] On a 940 I could get codes out with the key in position II.
[6] I did not always have the exact drill size so just used what I had to hand.

[classicracing]

Really excellent piece of work, thanks very much, are you going into production!
Richard

940 GLE HPT with this system
940 Sport with this system

[testhest]

Nice writeup.
Some one please make this sticky.

[lester08]

Thanks everyone, I hope it is useful.

A correction to Note [5], I can if fact get codes out with the key in position II, I think it was so fiddly when I tried this with paper clips I couldn't get it to work. (I would fix this but I don't seem to be able to edit my own post!)

However, with the engine running codes only seem to be available around tick-over, I guess the micro computers are too busy when the engine is at revs.

Also I can confirm the instructions for deleting codes provided by Jod T5 work fine with a 940.

[testhest]

Anyone know how to get this thread moved into the articles section? I think it really deserves to be in the article section of this board.

Once again, thanks for a good writeup.

[cumbrianmale]

Originally Posted by testhest

Anyone know how to get this thread moved into the articles section? I think it really deserves to be in the article section of this board.

Once again, thanks for a good writeup.

Done

Thanks for flagging it up.