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If it's not really about tuning or wiring. Then it belongs in here.
I would like to control my stock in dash temp gauge with the haltech elite but im having difficulty in configuring it to work. To test the gauge I have connected the wire that controls the gauge to the positive terminal of a AA battery (1.5v) and ground the negative from the AA battery, the gauge moves to the half position (between cold and hot ) IF I connect 2 AA battery in series (3v) to the same wire, the temp gauge displays pointer on C (Cold).
Now that i know the values that move the Gauge to those points I would assume it should be fairly easy to setup a table based on the coolant temp sensor values i can output various volts say between 0-5 volts to an output that connects to the same wire that I have mentioned. The issue with this is that in the elite i can only setup a DPO via use of a duty cycle etc (from my vary limited knowledge). This is were i am confused as i have tried to use the % value from 10 to 100% with duty Frequency set at 100hz and there is no movement on the gauge. I have also tried 50hz, 1000hz etc and no movement. What am i doing wrong?
Is there a way to output 0-5v rather that duty cycle or Is there something that I am missing.
I am a newbie and have very limited knowledge in these sort of things any help would be appreciated. Just in case one is wondering Why i am doing this, The reason is that My old stock gauge is damaged and the only other stock gauge that was available was one from the same model car out of Europe and it seems that the model in that country has the either the stock ecu control the gauges and or uses different value sending units etc my model is a Japanese Nissan primera.
Its a really nice gauge and i would like to use it, After wiring in the new guage i noticed that both the fuel and the temp guage were reading very high for example the temp would read extremely hot as in above H even when the car it not fully warmed up on a cold day or the fuel guage would be 1/4 when the tank is full. I wont get into controlling the fuel gauge just yet as I am confident that if i can sort the temp gauge the fuel is doable.
My thought is if i know what voltage places the needle where i want it, It should fairly simple to program the elite ecu to do just that. Any information or help would be greatly appreciated
Typically the temp gauge is not controlled by the ECU. The normal way of operating this is via a separate temp sender that is wired specifically to the gauge completely outside of the ECU. These temp senders are normally a single wire sensor and are separate to the sensor that the ECU uses for monitoring coolant temp. Alternatively in late model cars it's becoming increasingly common for the temp gauge to be controlled via a CAN message from the ECU.
Long story short though, no you can't output a variable voltage from the Elite ECU - The outputs only switch to ground.
You could probably achieve something close with a resistive voltage divider and capacitor (may need an inductor in series for current stabilization too) driven by the PWM output at high frequency if you no longer have the standard sender.
@ Andre: thanks for responding I am sorry it took so long for me to reply i have been away on work.
@ Slides : Thank you for your input slides, i read somewhere that someone achieved this by use of a resistor connected "inline/in series " from the ecu output to the temp wire that goes to the temp guage. They set a given frequency i believe it was 97hz and then they were able to control the gauge pretty accurately by using duty cycle. The resistor they used represented the a value in ohms that would send the gauge to hot without overshooting.
I should be able to figure out what resistor works for my stock gauge by monitoring the factory sending unit resistance as the gauge climbs from cold to hot which happens as soon as the car is warm (which is the reason for all this mess)
I also have another theory which i will try before going the route that we are discussing. My car is a 1996 4wd nissan primera p11 that has an sr20det turbo charged motor (from nissan avenir) Being that my new oem gauge cluster comes from a 2001 p11 primera from europe that has a QG18de engine I am wondering if the temp sending unit from the euro model differs from my car and hence by simply ordering that unit the values should correspond to the guage cluster i am currently using . This of course is a theory but its worth the try without having to get the haltech ecu involved. I will investigate further.
My other issue also is that the current gauge cluster does not read the gas level correctly but this may also be that the sending unit is completely different from the euro unit. The euro model sending unit will not work for my car due to my tank being a 4wd tank which uses a completely different baffle system . I have a fix for this though as there is a company in the US that sells a module/interface that makes any sending unit work with any gauge which has a set resistance range that is used in the industry and is also programmable if the resistance range is unique, so i am not too worried about the fuel level at this point. Not liking the 100+ price tag for this unit but i will look into it further once i get the time to sort out the temperature gauge. your probably wondering why not buy an original cluster for the car, well 2 things 1. I cant seem to find any locally and 2 i really like the euro gauge that has the white dials and just really a better unit. In addition to all of this my electrician already wired in this new gauge and apart from what i have mentioned all else works.
I realize this is several years old now and may not be of much use to the OP. But I was trying to find a solution to this same issue of trying to control an OEM gauge with an aftermarket ECU and came across this post. Fortunately, I didn't give up after reading this thread! Turns out it's actually very easy to control OEM gauges using PWM, at least certain types. If the OEM gauge sending unit uses a varying resistance to ground, like an NTC coolant temp sensor, all you have to do is disconnect the wire from the OEM sending unit and connect it to a digital pulsed output on the ECU, assuming the ECU has it's own input for that parameter, like engine temp. Then it's just a matter of setting up a table with the duty cycle that will give you the right readings on the gauge with the ECU switching to ground. The varying PWM duty cycle to ground emulates the varying resistance to ground of the OEM sending unit. Best way to determine the proper duty cycles for the table is by simulating the relevant sensor input to the ECU so you can determine the duty cycles needed for the full range on the gauge. Takes a bit of trial and error, but all you really need are min and max and maybe somewhere in between. Really depends on how many hash marks are on the gauge.
I did this with for the OEM coolant temp and oil pressure gauges in my 1973 Datsun 240Z using a Haltech Elite 2500 and it works great! Eliminated redundant wiring and sending units.
Appreciate the post, I've been wanting to do the same, eliminating a crappy 1 wire resistive oil pressure sensor and driving the oem gauge with an elite ouput. Thought it should work in theory so great to know its possible
i have done the same as @whitespeed with a few hondas and subarus.