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Speedometer replacement suggestions, please.


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Now that I "think" I might see my SE back on the road within the next month or two, I found I need to replace the OEM speedo with something else. The Motorsports LSD has no takeoff for the speedo so now I must figure something else out. Anyone have any suggestions, model numbers, size of hole to be filled, etc I can follow up on, as I would rather not have to depend on my Garmin. TIA.

 

MikieP

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Some info here

http://www.lotustalk.com/forums/f164/1994-s4-swap-electronic-speedo-126761/

 

more here

 

http://voicecrystal.com/Esprit/Gauges/index.php?start=6

 

Wire in ECU for speed signal 

ECU_Speedo_Output.jpg

 

Here's a good looking digital Caerbont

Dash_CaerbontSpeedo09.jpg

Dash_Lit_09.jpg

 

Just look for "Mark Wiens Caerbont" in google.

 

http://lotus.roadfly.com/turboesprit/2003-11/msg00399.html

 

 

 

Hi All,
  Just wanted to report the speedo is installed and working. For any of
you who'd like to do the same for 4 cyl mechanical speedo cars, let me
know and I'll save you some wiring time and headaches. Thanks everyone
very much for all your input... especially to Eric Fournier for being my
ear all day today! I may put up my pictures at some point, but here is a
list of notable tidbits;

1. The ECU 'does' output the VSS (Vehicle Speed Sensor) signal on the
red connector at J2-B8.
2. The VSS outputs 8 pulses per tire revolution.
3. There are spare female spade receptacle connectors behind the
headlamp/parking lamp switches, which provide power (green) and ground
(black) to the gauge (I think these were there for a voltmeter which
doesn't exist on my MY91).
4. The Caerbont gauge needs to be wired for a hall effect sensor input.
5. Using a female pin soldered to the signal wire, a secure connection
to the ECU pin can be made, even without removing the red ECU connector!
6. Finally... and with all my ducks in a row... in lieu of not finding
an existing, unused wire from the ECU area to the binnacle... I used the
old speedo cable as the conductor by clamping the wire from the ECU pin
to the end of the speedo cable and attaching an alligator clip to the
other end at the binnacle, wiring it to the speedo gauge signal input!!!
The mechanical speedo cable is well insulated and I did test for shorts
of it to ground and find it works just dandy, so I didn't have to hassle
running a special wire... and, well, hell... it's the speedo cable and
runs right up to the rear of the electronic speedo anyway... right?! :)
[duck, duck, duck, duck] Yes, I've definately gone mad, but at least I
put things to good use... heh.

  Even though I did all the calculations for tire size, pulses per
revolution and per mile, it still was reading a bit high. So I drove my
daily driver Prelude around town for a total of 5.4 miles and then did a
round on the same path with the Esprit, readjusting the speedo based on
the percentage of mileage difference until I matched the distance on the
new odometer. So it's close to my Prelude anyway... heh.

- Mark (91SE) Wiens  

Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Hi All,

 

Thank you for ideas! Anyone know what the size of the hole is (4"?) as I do not have my car close at hand? Anyone tried these?

 

http://www.speedhut.com/gauge/GR4-GPS-06/1/GPS-Speedometer-Gauge-200mph

 

Custom font, background and night coloring. Oof!

Edited by MikieP
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  • 7 months later...
  • Gold FFM

When my the mechanical speedo in my 90SE started acting up, I first tried to fix it by gluing the magnet back in, but there is to much play on the needle so the readings remain very erratic and not really useable.

So I read this and similar topics on the forum and decided to go for an electronic speedo. I managed to locate the OB wire near the ECM (not used in the SE) and trace it back to the fascia (as a NO wire), connected it to the speedo input for a hall-sensor and put the OB-pin into slot B8 at the ECM. Much to my regret and surprise, the speedo would not work. Checking with Freescan and Espritmon confirmes the ECM does know the speed from the VSS. However, when checking the frequency on pin B8 I got no readings. So it seems the ECM is not giving the required output. From what I read, I thought all Delphi ECMs have the output capability for an electronic speedo, even in the early cars that use a cable driven mechanical speedo. 

Can anyone shed some light on this? Could it be a setting in the early ECU?

Alternatively, has anyone tapped directly into the VSS to get the signal to the digital speedo?

 

Thanks,

 

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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  • Gold FFM

Thanks for confirming Derek. I'll open up the ECU tonight to see if there is anything wrong with the connection to pin B8. As sadi I have connected a frequency meter to it and despite Freescan giving a speed of up to 5mph when turning the wheel, the meter did not register any signal.

 

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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The four additional digital VSS outputs from Chip U18 are on pins 11, 12, 13 and 14. I am not sure which one of these is used and if it is connected directly to ecu pin B8 or if it goes through other components first. The value you see reported in Freescan is derived from a different output from chip U18 via the 16 bit I/O expander chip U9 into the P4 timer/counter chip U2.

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Glad you tried one on... Mine seems to sometimes lose speed due ? as am usually out in the open when it happens but otherwise I like it. Esp the gadgets in the electronics package. Being a hopeful sort, I went with the 0-200 version though. :driving:

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Hi Chris,

 

Be glad to except that 1) it is dark here now, and tomorrow have to pick up a 24' truck to pack 10 lbs of House goods to get 200 miles away with a crew of 5 and be back before midnight. Current shop did it for me, although are now dead to me - charged be $288 for 12.80 intake gasket and double billed me and billed me for things done wrong, and came undone or broke and destroyed brand new hand brake cables and lied to me about oil change being done et al.

 

Antenna wire was run through hole and down front trunk floor and then up to underside of front hood and glued. If all goes well tomorrow, will try pics on Sunday if sun comes out. but looks OK. did not seat all the way flush to the dash, though, at least they could not get it flush.

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This looks cool, probably extremely expensive. http://www.id4motion.com/

 

That does look nice :). Perhaps we could organise a group buy?

 

Would you still have to keep a mechanical odometer for the obligatory mileage reading?

Signature not working...

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  • Gold FFM

The four additional digital VSS outputs from Chip U18 are on pins 11, 12, 13 and 14. I am not sure which one of these is used and if it is connected directly to ecu pin B8 or if it goes through other components first. The value you see reported in Freescan is derived from a different output from chip U18 via the 16 bit I/O expander chip U9 into the P4 timer/counter chip U2.

 

Thanks again for the detailed information! We checked for continuity (without power to the ECU off course) but didn't find any between chip U18 and pin B8. I put the ECM back in so I can keep driving the car, using a GPS for speed, but I do need to sort this quickly...

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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  • 2 weeks later...
  • 1 month later...
  • 1 month later...
  • Gold FFM

I finally got my speedometer to work, thanks to tech support from CAI.

Apparently the output from the ECM is an open collector output, and the output transistor needs a load resistor to generate the signal.

This is provided inside the speedometer by connecting the red wire to 12 volts (for a Smiths International).

I did have to use the red/blue wire for low-voltage signals instead of the black/white one the manual suggests for an ECM signal.

 

Haven't taken the car out yet, but tests were good, so I'm hopeful all will work as it should.

 

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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  • 4 years later...

Hi All, 

I'm considering a GPS speedometer for my S4s. I've already looked at some available options and have a few questions: 

1. The speedo hole (in the dash) size is 98 mm, or 3-7/8" (which is about the same as the diameter of the speedo body itself). The diameter of the speedo face (bezel) is 104 mm, or 4". Can S4s owners please confirm this if possible? 

2. This (already considered on this thread) seems to be a good option and the right size: https://www.speedhut.com/gauge/GR4-GPS-03/1/GPS-Speedometer-160mph. Looking at their wiring instructions, I'm just not sure how to use the S4s 3 existing speedo wires (Black: ground; Green: power; Orange/Brown: speed signal) for the new speedo, but I'd imagine I should reuse the ground and power wires? And also, for the lighting, which existing dash wire is the best to use? If somebody who installed one of these can advise, it will a great help. There is one snag though: their lead time (to actually manufacture the gauge) is 4 weeks. 

3. Here is another (thanks to Atwell for advice): the only 4" size is this one: https://www.autometer.com/4-speedo-180-mph-elec-cobra.html#, does anybody have experience with one of these? 

Please advise, thanks a lot in advance.

Anton

'95 Esprit S4s

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  • 4 months later...

Hi All, 

I successfully replaced the old non-working speedo on my S4s with a new GPS one and it works fine. However, sometimes CEL comes on and off (may be a few times during a ride, and not on every ride), after which I read the code (with a paperclip method and via Freescan) to be the code 24 - VSS (vehicle speed sensor). From the 3 existing speedo wires, I'm reusing the two: ground (black) and power (green), but not the 3rd one: speed signal (orange). It seems that ECU at times senses there is no connection to the speedo (probably via that orange wire) and generates that code 24. Is there a way to fix this? Something like connecting the unused  orange wire to a resistor or something similar? 

Please kindly advise, thanks in advance. 

Anton 

'95 Esprit S4s

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Derek, thank you, so you are saying that the connectivity between VSS and ECU is intermittent? I checked it multiple times and it was always good. Besides, I replaced the VSS with a new one. All that - prior to replacing the speedo. So to speak, I don't need VSS anymore, not for the new speedo anyway. If so, how can this be fixed? 

Barry, thank you, how is VSS related to fueling, can you elaborate? 

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