posted by
someone claiming to be John Sullivan
on
Mon Nov 28 12:24 CST 2005 [ RELATED]
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Folks,
I have progressed enough in installing a '93 engine and wiring looms, along with SRS, into my '86 245 body with M46, and I have a few problems remaining that I think I can solve, but I have one that I don't know how to deal with. The speedometer does not work.
This is a hybrid setup necessitated by not having a '93 rear end. What I did was take an electronic speedometer marked "9800" from an earlier electronic cluster and put it into the '93 cluster, in place of the one there marked "40800". That way, my 86 rear end should drive the speedo OK, but I would also benefit from the SRS test light and the little set of SRS electronics that are on the cluster board. I also wanted to have the upshift light for my '86 M46 and a light to indicate that the overdrive was engaged, as in the '86 cluster. I discovered hat the '93 FCU provides the upshift signal for manual transmissions, and I tried to wire the ABS light (no ABS on my ’86) to indicate that the M46 overdrive is engaged. That took a little research and rewiring, but nothing complex.
When I started the engine a couple of weeks ago, after more than a year, it turned over and warmed up nicely--to my amazement! The speedo, however, didn't seems to act correctly. When I had turned the ignition on, the speedo rose to indicate a high speed, and when I started the engine, it dropped to zero. That symptom is repeatable.
I disregarded that while I bled the brakes and did the other preliminaries to getting the car rolling, hoping that the speedo would work once the car was underway. Well, it doesn't; it sits at zero regardless of the car's speed. I investigated what was going on at connector 233 (the three-wire thingy that is held in place with a white cover). The blue wire to it (pin 3) reads 12 volts whenever the ignition switch is on, and that is consistent with the ’93 wiring diagram. The black wire (pin 1)shows a few tenths of an ohm resistance to ground, which also seems correct. That leaves the wire to pin 2, which (unless I screwed up earlier) connects through the loom to the speed sensor on the differential case. The speedomoter's behavior indicates that this wire improperly picks up a positive voltage when the ignition is turned on, and that that voltage drops to zero when the engine is started, and that speed sensor pulses never get to the speedo though that wire—or the speedo doesn't recognize them.
In case it isn’t obvious, I'm in over my head on this one, and I'd be grateful for advice from those knowledgeable of electronic speedos. I’m investigating the archives, but I don’t expect I’ll find anything directly relating to this problem—which I am guessing is self-induced.
Thanks for any thoughts.
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The rear connector wiring is different for '90-93, '88-89 and '85-88 speedomneter. You may get an 88 or 89 to work, but a '91- will defintitly not work in pre '90- speedo's. It isn't that one is ABS, they are wired differently to the pins on the connecrtor cluster, and the boards are different layouts.
I took a '91 speedo cluster to try to replace an '89, and had to re-build the '89 with the '91 parts. In doing so, I found that an '86 would not work wiht the M47 up-shift light and bulb warning circuit, as well as the panel illumination. I did use the '86 diff sender with the '89 speedo which actually read closer to actual speed, reducing the speedo error I always had with the orig '89.
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'89 245 sportwagon, destroyed by hit & run driver, RIP. '04 V70 2.5 T Sportwagon, 12k mi and '91 245 5-speed, 209k mi, replaced the '89
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Thanks, Pete.
Sounds like you traveled a similar, if not identical, road.
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jds
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Well, you can't swap a 92-93 cluster into an earlier car and get any function so different are the two speedo/clusters. That must be at the heart of the whole problem here but that is all I can say.
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Thanks, Bob
As I had transplanted the entire wiring loom from a '93, including the connectors to the cluster, the only problem I anticipated with the speedo itself was the fact that the rear end remained '86, with a 12-hole "Tone ring", and a '93 speedo wants to see a 48-hole tone ring. Therefore, I installed a '91 speedo in the '93 cluster. If fits the board physically (which the '86-89 speedos don't) and it looks for a 12-hole tone ring. So I hoped it would give me good speedo and odometer outputs. Not so, at least not yet.
Based on Art's response and partial disassembly this evening, I have confimed that the '91 speedo (unlike the '93) wants to see ground on pin 2 rather than pin 1 of the three-wire connector, so I will be proceeding on that basis.
The other lights on the cluster and the guages work OK, although I can't get the SRS light to go off -- there might be some good reason for that, and I will address it later.
Thanks again.
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jds
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Hey John,
Given your verification of the wiring, I can't shed any light on those weird symptoms. If you get together with someone who can, you might be able to make use of my notes on the pre-ABS speedos found in a link near the end of this page http://cleanflametrap.com.
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Art Benstein near Baltimore
The youngest pope was 11 years old
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Update on this puzzle:
The unused ABS loom held no secrets. Looks like it would just tap off a sensor input for the ABS to use rather than modifying the basic signal to the speedo.
I switched pin 1 and pin 2 wires on the speedo connector. Now the speedo (a 10048 unit, assembled in Feb 91) goes to 120mph when I turn on the ignition and stays there until I turn off the ignition, whether or not the engine is running. Completely wrong, but in a simple way. The rest of the car continues to ignore the speedo, remaining stationary except when I kick it.
The components on the speedo circuit boards show no visible damage so far.
The resistance from pin 1 to ground (or to pin 2) is 3500 to 4000 ohms, and I believe that's what the sensor's resistance is supposed to be.
Tomorrow, I'll try to confirm:
1. What voltages actually are on pins 1 and 2 with the ignition on and off.
2. Where the voltages are actually coming from. Should be from the sensor, of course, and I imagine they should be zero unless the rear wheels are turning.
2. Whether re-installing the '86 speedo helps, though I can't imagine why it would.
Anyone have ideas not yet posted? Thanks
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jds
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Hi JD,
I would dearly love to have the answer that would get your car in synch with the speedo. We could both make a lot of money on zero to 120 in less than a second.
Next to me I have open a pair of wiring diagram manuals, for 91 and 92. I see why anyone would tear out hair making sense of the connections. ABS or no, the drawings are contradictory even on one page; showing G gauge terminal grounded in one spot and the odd reversal of terminal 1 and 2 numbering, so they go 2-1-3 for gauge, ground and + respectively.
Frankly, without being able to prove it by experience, I don't believe they changed the plug positions for the respective functions. This would be a foolish move with no advantage I can imagine. My bet is the documentation is in error like it is in many other places.
I know the color codes did change, as I showed in images of an 89 and 91 side-by-side, but the board layout changes I refer to are internal, and not changes in the pin functions. It is confusing to use the blue wire for a gauge input one year, then use it for power the next.
Also, after looking at the diagram I made of the internal workings of the gauge, I can't see you could harm the speedo with reverse polarity anywhere on the three-wire plug. A diode protects the power circuit, and the gauge input is protected by a high resistance. But I wonder if the meter could deflect if power was wired correctly but gauge and ground got reversed, or some other defect could leave the gauge ungrounded. The current needed to operate the needle may find its return through the gauge input or even the ECU speed signal output.
I believe your sensor resistance can be found in Bentley, and I recall it changed a great deal on the way to ABS and beyond. Post back if you don't have the Bentley, I'll dig it out.
(1) I won't quote pin numbers with all the confusion on numbering, but I think black remained ground throughout, and is the center pin. Not sure where your old harness meets your new one, but the old gauge wire may have been blue; the new one white/green.
(2) You should only see voltage on the power lead - unfused ignition. The sensor voltage isn't worth trying to read (imagining you extending the wires to a meter on the passenger seat), the resistance check is sufficient.
(2 the other 2) I believe the 86 speedo should be a valid substitute for basic testing.
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Art Benstein near Baltimore
Q. What do bulletproof vests, fire escapes, windshield wipers, and laser printers all have in common?
A. All invented by WOMEN!
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Thanks, Art,
I appreciate your continuing to mull this over.
Even though it makes no sense (and is not the problem just now), I believe Volvo really did indeed reverse the sensor and ground wires in the 93 (and maybe the 92 -- in fact, maybe all the ABS-ready cars), because the loom I installed from the '93 had the GN-W wire on pin2, the BK on pin 1.
Moreover, diagrams in the green 93 green diagram manual show it that way.
(1) The ABS page shows the ABS brain sharing the speed signal from the sensor with the speedo, using green/white wires, and that for the speedo is shown going to pin2. Note they had to create this diagram and picture when ABS was introduced.
(2) The speedo diagram itself show GN-W on pin 1, but labels it as pin 2 -- to allow them to use the old diagram and picture with minimum modification?
(3) The cluster (combined instrument) diagram labels the GN-W signal wire as going to pin 2, but the accompanying picture show it on pin1 -- they forgot to change that??
(4) Not directly related, but the '93 output from the speedo to the FCU and Cruise control is shown going through pin 6 on the round connector (#31), and seems also to be available at connection 203 on the back of the cluster -- which I take to be the double male lug (labelled 200 rather than 203) on the picture accompanying the diagram. Pin 6 does other things on earlier clusters (battery light, I think).
But...none of that should matter much since I put a K10042 (thus non-ABS) speedo into what I remembered to be a '93 cluster. The speedo's board has the componnt arrangement of the "new" board in your pictures, and I checked that its pin 2 goes to the multiple ground pins on the ITT IC. So I reversed the GN-W and BK wires on the car's loom, with the effect I reported. Speedo pegs whenever ignition is on, but doesn't get damaged.
Throughout all the diagrams, by the way, pin3 is shown with a switched blue wire from the ignition, which is consistent with what I am looking at.
My multimeter show 6v at the BL wire on pin3 -- good
Ii shows continuity to chassis gnd for the BK wire, now on pin 2 -- good.
What's coming to the green-white wire on pin1? I'm not sure. I'll just disconnect it and see what the speedo does. If it still goes full-scale, that will tell me something new, like maybe the speedo really is faulty (I got it used -- FCPII in Upper Marlboro -- and I have no proof it works). I'll report back
Agan, thanks for the informed sympathy.
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jds
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Aha!
I took the GN-W wire off pin1 and turned on the ignition. The speedo went full scale.
I removed the round plug. The speedo still went full scale
I removed the half-moon plug. the speedo still went full scale.
I removed all the other wires but connector 233. The speedo still went full scale
So it goes full scale as long as 6 volts is on pin3 and pin2 is grounded, even when there are no other connections to the speedo or to the rest of the cluster.
Perhaps the speedo board is faulty (even though it looks great!)?
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jds
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Hi JD,
I'm only having difficulties with two of your findings. Pin numbers mean nothing to me unless we agree on their physical location, assuming they are consecutively numbered. Are they marked anywhere? Maybe on the pin housing? The circuit boards I have are marked with the G, upside-down T, and +, for gauge, ground, and power respectively. The marking is in foil.
Question: You say the 93 runs the green/white from the gauge sender to pin 2 both in your harness and the manual? Does that mean your harness came with green/white in the middle position?
Question: Are you serious about only 6V on the power lead? That is where I would start looking. Should be battery voltage.
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Art Benstein near Baltimore
Today's mighty oak is just yesterday's nut that held its ground.
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Hi, Art,
I was serious about the 6 volts, but I really meant battery voltage (Mental lapse took me back to my '61 VW, where battery voltage was 6 volts). So I'm happy with the 12v that is actually coming in on the blue wire.
I found pin numbers embossed on connector 233. It says that pin 3, with the blue wire, is alone on one side of the slot in the board. Pins 1 and 2 are together on the other side.
And yes, on the '93 loom, I found the the GN-W wire originally installed in the center location. BK was on pin 1.
By the way, I was thinking I would have to do some cutting and splicing to switch wires on connector 233, but I found it opens up when you find the right place to apply some pressure, and the wires are readily switched around.
So, because my 10042 speedo head is pre-'92, I switched the GN-W wire and the BK wire on the connector. That grounds pin 2, which connects on the PCB of this unit to the big grounded pins on the IC -- the six pins that your diagram shows going to ground. I found continuity between them and pin 2 with my multimeter.
Having done that, I reinstalled the head in the cluster and the cluster in the car and found that the needle on the 10042 unit now goes full scale whenever battery voltage is applied between the blue wire and and the BK wire, even when the GN-W wire is disconnected altogether (and even when all the other wires to the cluster are disconnected.)
Now, that can't be right, but it does -- I believe -- isolate the diffculty to the speedo itself.
I looked around for another yesterday (89-91 are -- I believe -- the years for units that are designed for the 12-hole tone ring, and also fit into a '93 cluster), but I didn't find one.
Haven't tried Crazy Ray's yet, but I've been to all his places before.
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jds
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Hi JD,
OK, I agree you must have a kaput meter now. Only thing I knew to kill them was putting the coil wire (red-white tach lead) on the terminal for the cruise take-off, but it sounds like you have a dead one. That is, just allowing for differences in technique, if you have those actual voltages while the unit is connected and the needle is pegged.
Thanks for the clarification on the 93 wiring. Good thing to keep in mind and watch out for-- and contemplate why they would do such a thing. Enforced incompatibility?! Whatever, the swap wouldn't kill the circuits I've seen.
BTW, I actually saw fairly intact clusters in some of the 240s I looked at in that Mt. Airy yard. Most other locations have been gone through for odo gears, reset buttons and halogen lamps. That was over a month ago.
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Art Benstein near Baltimore
Time flies like an arrow. Fruit flies like a banana.
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Thanks, Art,
I would't swear I didn't do that, but I know better.
I'll start at Mt. Airy, when I am next free to roam.
Meantime I'll see what happens when I put an '86 or '87 cluster in (after having made sure its round/half-moon connector differences won't do damage elsewhere, like to the ECU.).
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jds
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Hi JD,
Why not substitute the 86 or 87 speedometer outside of the cluster mounting, just for a test? The only requirement from the cluster stick pins you'll be missing, is the flex fuse. You can stick a hunk of wire in to bridge the two sockets as I did in the second picture here . This should avoid all the other changes VDO and Volvo threw in over that span of years.
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Art Benstein near Baltimore
In democracy it's your vote that counts; in feudalism it's your count that votes.
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Hi, Ben,
I somehow missed your post, although I've been lurking.
But I did what you suggested, in a way. This morning, I took apart the '93 cluster and an '87 cluster I found. I discovered that the '87 speedo fits right into the '93 cluster mechanically and the electrical pins line up fine (this doesn't work the other way around, because the '91-93 speedos have an additional PCB board, which I gather turns on the service light -- looks like that board could be removed without losing any other function, however.)
Anyway, I replaced the '91 K10042 speedo that had been in the '93 cluster with the '87 K9800. I took it to the car and gingerly tested the new setup by adding wires and plugs to the rear of the cluster one at a time, turning on the ignition with each addition. The speedo needle didn't move -- which was encouraging.
So I backed out of the drive, held my breath and started forward. The needle moved up just fine, so I'm one step closer to being ready for the road.
And now I know for sure that the old version (86-89)and new version of the speedo board (90-91) can be interchanged -- maybe you already knew that. Anyhow, many thanks for your encouragement and guidance during this experiment.
Unfortunately, the odo doesn't work. Would a stripped gear be the only cause for that? What I mean is: is the working speedo needle evicence that the odo stepper motor is also working?
Nor is the SRS light going out after 10 seconds, as it should, but that's a problem for a warmer day.
Thanks again,
jds
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Hi John,
I read vvpete's response, so I know you've already got the correct answer. The odo stepper can be working fine, but its output is geared and most susceptible to breaking.
Commonly posted here is the notion the gear suffers damage when the trip reset is pushed during travel. I don't know from experience, but I have collected a few gears in the pick'n'pulls that looked intact, but in one case only survived briefly after being installed in another brickster's speedometer.
I could see where the later version with the service counter could really load the gear if the counter was faulty or ignored. When this finally happens to one of my cars, I'll try one of the old brittle gears I saved, with the thought in mind to buy a new gear if not successful.
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Art Benstein near Baltimore
Every calendar's days are numbered.
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Hi, Art,
I don't know how significant a mechanical load the second board creates, but I would guess that the added worm gear on the odo gear train continuously turns the single flat gear (on the service light board) that meshes with it. That flat gear seems to have a built-in electric contact that conducts once per revolution. The electronics on the rest of the board might just count the turns of that shaft.
After 30K worth of turns, the board would ground the appropriate side of the bulb that is installed in the SERVICE LIGHT socket of the instrument cluster. That ground is probably through the single rigid U-shaped wire that plugs into to the service light board and the instrument cluster's PCB, from behind (wish I had your camera.
Unfortunately, that straightforward view is not supported by the fact that flipping the lever resets the 30K counting process: after all, flipping the lever seems to do nothing but momentarily unmesh the worm gear and the flat gear, at which point the flat gear must be spring driven to a reset position. That makes it more likely that the flat gear mechanism is more complex and produces more load than the simple explanation would indicate -- all the more reason to get it out of there.
I guess the service light board uses the twin brown wires from the main speedo as +12V and gnd for its internal components only. If that's true, I think one could just clip the brown wires, remove the two screws holding the board in place and take it off, eliminating whatever mechanical strain in the odo gears it creates.
Then the speedo head could also fit into speedo clusters all the way back to '86.
I've been wondering how the 2115 ICU can be used in all these speedos with their different K-values, and I just came across a 700/900 FAQ entry that talks about calibrating a 2115-based speedo by changing the value of the resistor on pin 4 (his pin 4, maybe not your pin 4). I don't understand all your comments on the circuit board, but you wrote something about one low-tolerance resistor setting a time constant. Do you know if those ideas (pin4 resistor -- calibration) are connected? If so, would the odo also be affected? I am guessing maybe not.
Thoughts?
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Final Report. I finally found the instrument cluster I had taken out of the '86. I moved the speedo head from that cluster to the '91 cluster (which I had previously thought a was a '93 cluster).
Before installing the speedo head in the '91 cluster, I checked its odo gear, and it was good. When I put the cluster in the car, the speedo worked and the odo worked. So I now have the original speedo head back in the car it came from,, which in other ways has '93 stuff. The odometer, of course, reads the actual mileage on the car, so I won't have to do any paperwork with DMV.
By the way, as suggested, I found that a bad gear caused the odo on the '87 speedo head I reported on last time to be inop.
I have routed the 5th gear light wire from the manual overdrive relay to the ABS light on the cluster. Because that light has battery voltage on its other terminal whenever the key is on, however, it goes off when the overdrive is on, and vice-versa. I will have to install a relay to reverse that situation, and then use an exacto and some glue to replace the yellow "ABS" window with a green "5" window.
Then, on to the SRS challenge.
Thanks to all who commented and contributed as I worked the speedo problem.
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jds
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The speedo can work but the odometer gear can be missing a tooth which is pretty common. You should be able to remove the gear and swap in a known good one from any year speedo.
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'89 245 sportwagon, destroyed by hit & run driver, RIP. '04 V70 2.5 T Sportwagon, 12k mi and '91 245 5-speed, 209k mi, replaced the '89
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Thanks, Pete,
I've got an intact gear from another head now, and I'll put it in.
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jds
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Thanks, Art,
I have downloaded a copy of your speedo info, and I'll study the devil out of it.
I noted right off the bat that my wiring loom's conector 233 has the ground connection on pin 1 and the green/white wire on pin 2 -- correct per my '93 green diagram book. Your photos and diagram of the earlier setup show the wires the other way around. Unfortunately, when I reversed the wires on my loom, the problem didn't go away, just became rather different, so I switched back pending a brainstorm. I hope I don't burn anything out in all this.
I am currently examining the ABS harness I retrieved from the '93 donor, but didn't install, to see whether its wiring holds some clue.
Thanks also for the other items on your page. I have a third seat to install and a very dim clock.
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jds
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